i received a private message regarding this thread.

the answer to this problem should definitely be (a).

the pronoun "it" in the first three choices is just fine; this is an example of the only exception to the normal pronoun rules with which you need to be familiar.
for more on that topic, please visit this thread:
https://www.beatthegmat.com/pronoun-ambi ... tml#312862

the verb tense in (b) ("had approved") is nonsense, since that tense suggests that the energy proposals had already been improved by the time of this groundswell in public opinion.
"inevitable" suggests the idea that something cannot be avoided -- but is only used when we are talking about something that hasn't happened yet (or hadn't happened yet, at the time of a past-tense example). therefore, "would" in (a) is a logical tense.

for more on the use of "would" to discuss an action that was in the future at one point, see here:
https://www.manhattangmat.com/forums/pos ... tml#p45300

(c) is idiomatically incorrect in two different places -- you can't use "of" or "to" with inevitable -- but, as has been posted elsewhere on this board, gmac has announced that they are no longer testing these kinds of idioms. (they may still test idioms when the idioms involve actual changes in the meaning of the sentence, but, according to the announcement i saw, they won't test random ones like these.)

as for the last two choices, consider the meaning of the sentence: what is the senate going to approve? they are going to approve the president's energy proposals. therefore, it's illogical to insert any other modifiers between "approve" / "approval of" and "the president's energy policies".

by the way, "groundswell" should be one word, not two; i assume this was just mis-transcribed.