This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 222
Joined: 13 Oct 2008
Thanked: 3 times
Followed by:2 members

Strengthen

by venmic » Thu Dec 08, 2011 5:10 pm
Can anyone help me with this - Thanks

The attrition of tooth enamel stems from erosion, which occurs only when teeth grind against hard substances. Therefore, those who regularly clench or grind their teeth together will suffer higher rates of enamel attrition than those who do not.

Which of the following most strongly supports this argument?


(A) Tooth enamel can be chipped in sports accidents.

(B) Grinding and clenching both have the same effect on tooth enamel.

(C) Tooth enamel is an extremely hard substance. correct

(D) Most people do not grind or clench their teeth together.

(E) Front teeth are more likely to grind against one another than back teeth are.

why C

GMAT Instructor
Posts: 1302
Joined: 19 Oct 2009
Location: Toronto
Thanked: 539 times
Followed by:163 members
GMAT Score:800

by Testluv » Thu Dec 08, 2011 9:48 pm
The first sentence is evidence--erosion requires grinding against hard substances.

The second sentence is conclusion those who grind their teeth are more likely to suffer enamel attrition.

The mismatched ideas in the evidence and conclusion are "hard substances" and "teeth". The author is assuming that teeth are hard substances (if they're not then the conclusion doesn't follow from the evidence).

(C) strengthens the argument by backing up this assumption.
Kaplan Teacher in Toronto

User avatar
Master | Next Rank: 500 Posts
Posts: 296
Joined: 29 May 2011
Location: Vietnam
Thanked: 10 times
Followed by:5 members

by tuanquang269 » Sat Dec 10, 2011 12:02 am
venmic wrote:Can anyone help me with this - Thanks

The attrition of tooth enamel stems from erosion, which occurs only when teeth grind against hard substances. Therefore, those who regularly clench or grind their teeth together will suffer higher rates of enamel attrition than those who do not.

(C) Tooth enamel is an extremely hard substance. correct
The premise is: The attrition of tooth enamel stems from erosion

Erosion occurs only when teeth grind against hard substances

Conclusion: those who regularly clench or grind their teeth together will suffer higher rates of enamel attrition than those who do not.

We lack the information What is hard substances. Choice C connect hard substance with tooth enamel.