Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemandStart anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions

Investigation of the floor of the Black sea (Exampack 1 CR)

Expert replies
by bluejay210 » Sat Aug 09, 2014 7:09 pm
From GMAT PREP EXAM PACK 1

Investigation of the floor of the Black Sea, a saltwater sea connected with the Mediterranean Sea by a narrow channel and remote from other seas, has revealed deposits of freshwater shells dating from 5500 B.C. on an ancient shoreline. That shoreline lies 500 feet below the Black Sea’s current level, and the sediment just above it contains the remains only of saltwater creatures. Scientists hypothesize that about 5500 B.C., seawater from the Mediterranean overflowed into the Black Sea basin.

Which of the following would it be most useful to ascertain in order to evaluate the scientists’ hypothesis?

A. Whether the body of freshwater whose shoreline was uncovered was less than 500 feet deep
B. Whether the remains of saltwater creatures contained in the layers of sediment that lie just above the ancient shoreline differ significantly from those contained in the topmost of layers of sediment in the floor of the Black Sea
C. Whether any of the freshwater shells show indication of having been used as tools
D. Whether there are traces of an ancient shoreline of the Black Sea that lies significantly less than 500 feet below the sea’s current level
E. Whether the remains of the saltwater creatures found in the sediment closely resemble the remains of Mediterranean saltwater creatures from the same period.

[spoiler]OA:E[/spoiler]

Please help explain the logic!!!
Join the discussion
Source: — Critical Reasoning |

by GMATGuruNY » Sun Aug 10, 2014 5:35 am
bluejay210 wrote:From GMAT PREP EXAM PACK 1

Investigation of the floor of the Black Sea, a saltwater sea connected with the Mediterranean Sea by a narrow channel and remote from other seas, has revealed deposits of freshwater shells dating from 5500 B.C. on an ancient shoreline. That shoreline lies 500 feet below the Black Sea’s current level, and the sediment just above it contains the remains only of saltwater creatures. Scientists hypothesize that about 5500 B.C., seawater from the Mediterranean overflowed into the Black Sea basin.

Which of the following would it be most useful to ascertain in order to evaluate the scientists’ hypothesis?

A. Whether the body of freshwater whose shoreline was uncovered was less than 500 feet deep
B. Whether the remains of saltwater creatures contained in the layers of sediment that lie just above the ancient shoreline differ significantly from those contained in the topmost of layers of sediment in the floor of the Black Sea
C. Whether any of the freshwater shells show indication of having been used as tools
D. Whether there are traces of an ancient shoreline of the Black Sea that lies significantly less than 500 feet below the sea’s current level
E. Whether the remains of the saltwater creatures found in the sediment closely resemble the remains of Mediterranean saltwater creatures from the same period.

[spoiler]OA:E[/spoiler]
Premises:
The floor of the Black Sea has deposits only of FRESHWATER CREATURES, implying that -- at one time -- the Black Sea was composed of fresh water.
The sediment just above the floor contains the remains only of SALTWATER CREATURES, implying that -- at some point -- the Black Sea was transformed from a freshwater body to a saltwater body..

Conclusion: Seawater from the Mediterranean Sea overflowed into the Black Sea basin, transforming the Black Sea from a freshwater body to a saltwater body..

For evaluate CRs, rephrase the answer choices as STATEMENTS.
The rephrase of the correct answer choice will either STRENGTHEN or WEAKEN the conclusion.

Answer choice E, rephrased:
The remains of the saltwater creatures found in the sediment closely resemble the remains of Mediterranean saltwater creatures from the same period.
This rephrase establishes a link between MEDITERRANEAN SEA and the SALTWATER CREATURES whose remains have been found in the Black Sea, STRENGTHENING the conclusion that seawater from the Mediterranean Sea overflowed into the Black Sea basin.

The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Join the discussion