Sentence Correction

In an effort improve the quality of patient care, Dr. Lydia Temoscho is directing one of several clinical research projects that seek to determine the extent that psychological counseling helps to supplement the medical treatment of serious disease.
(A) seek to determine the extent that psychological counseling helps to supplement
(B) seek to determine how helpful psychological counseling is in supplementing
(C) seeks to determine how helpful psychological counseling is to supplement
(D) seeks to determine to what extent psychological counseling is a help in supplementing
(E) seeks to determine the extent that psychological counseling is helpful in supplementing

Doubt: Shoudnt "seeks" be used as it refers to a singular subject "one of several clinical research projects"
Why cant the answer be "E"

Correct Answer is "B"

Source: Test Code 42 GMAT Test Paper

keepsmilinyaar wrote:In an effort improve the quality of patient care, Dr. Lydia Temoscho is directing one of several clinical research projects that seek to determine the extent that psychological counseling helps to supplement the medical treatment of serious disease.
(A) seek to determine the extent that psychological counseling helps to supplement
(B) seek to determine how helpful psychological counseling is in supplementing
(C) seeks to determine how helpful psychological counseling is to supplement
(D) seeks to determine to what extent psychological counseling is a help in supplementing
(E) seeks to determine the extent that psychological counseling is helpful in supplementing

Doubt: Shoudnt "seeks" be used as it refers to a singular subject "one of several clinical research projects"
Why cant the answer be "E"

Correct Answer is "B"

Source: Test Code 42 GMAT Test Paper

verb following relative pronoun "that" should point to projects and not
"one of the projects"

Here are 2 sentences that I came across that explain this subtle
difference --

1. Each of the books reminds me of her
2. Each of the books that rest on the table reminds me of her

In (1), reminds correctly refers to each of the books

In (2), introducing "that" requires the use of a plural verb
to refer back to "books"

Wow...it stumped me too...I thought it should be seeks and not seek!

Thanks jay!

Why answer A is incorrect?

thegmatbeater wrote:Why answer A is incorrect?

extent that is unidiomatic, extent of or extent to is preferable.

ildude02 wrote:

thegmatbeater wrote:Why answer A is incorrect?

extent that is unidiomatic, extent of or extent to is preferable.

Are there any other reasons why B is better than A?

"that" unlike "which" can modify a long phrase also. so when do we know that "that" is only modifying projects and not "one of the projects". Can anyone explain