Twenty-two feet longand 10feet in diameter, the AM-1
is one of the many new satellites that is a part of
15years effort of subjecting the interactions of Earth's
atmosphere, oceans. and land surfaces to detailed
scrutiny from space.
(A) satellites that is a part of 15 years effort of
subjecting the interactions of Earth's
atmosphere, oceans, and land surfaces
(8) satellites, which is a part of a 15-year effort to
subject how Earth's atmosphere, oceans, and
land surfaces interact
(Cl satellites, part of 15 years effort of subjecting
how Earth's atmosphere, oceans, and land
surfaces are interacting
(Dl satellites that are part of an effort for 15 years
that has subjected the interactions of Earth's
atmosphere, oceans, and land surfaces
(El satellites that are part of a 15-year effort to
subject the interactions of Earth'satmosphere,
oceans, and land surfaces

In this question, we are talking about one of the many satellites, so shouldn't it be the first answer choice as it uses the singular form of verb.

Thanks in advance

Edvento,
The question is from the Verbal OG SC section (#42) so i don't think the answer can be incorrect.
The detailed explanation of the answer is attached below. Please help me understand why we can ignore the required use of a singular verb. In fact the explanation says that a plural verb should be used for satellites but what about the fact that its one of the satellites?

A The relat ive pronoun that refers to satellites,
so it should be followed by the plural verb
are; effort to is th e correct idiomatic
expressio n; as an adjective, 15 years becomes
15-year.
B In this version of the sentence, it is unclear
what the relative pronoun which refers to- if
it refers to sate//ites, it should be followed by
a plural verb. Presenting the object of the
verb subject as a phrase beginning with how
and ending with th e verb interact produces a
sentence that seems to be about how variou s
conditions react to detailed scrutiny from
space .
C This sentence too seems to be making a
nonsensical statement about how conditions
are interacting to detailed scrutiny. It is
not clear whether part refers to sate/lites or
the A M -1.
D Thi s version is wordy and confusing because
of the sequence of relative clauses begin ning
with that.
E Correct. The senten ce is clearly worded and
logically coherent.

Thanks a lot for your help!

OG explanation says that in C, part may refer to satellites or to the AM1. I don't understand how 'part' can refer to AM1. 'Part' is preceded by 'satellites,' . So I believe it clearly refers to satellites and not to AM1.

Please help.
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OA is E..

Kindly clarify the following doubt of mine.

OG explanation says that in C, part may refer to satellites or to the AM1. I don't understand how 'part' can refer to AM1. 'Part' is preceded by 'satellites,' . So I believe it clearly refers to satellites and not to AM1.
_________________

hope is a good thing, maybe the best of things. And no good thing ever dies.

Who says you need a 700 ?Check this out : http://gmatclub.com/forum/who-says-you-need-a-149706.html#p1201595

My GMAT Journey : end-of-my-gmat-journey-149328.html#p1198742