Policy makers remain concerned about the prospect of inflation, althou

I'm happy to help with this.

First of all, when we say someone "remains concerned", this implies they have been concerned for a while and are still concerned. Adding the word "still" contributes absolutely no new information. The construction "still remains" is 100% redundant and always wrong. Therefore, right away, (B) & (D) are out.

This is a subtle grammar point. A proposition can have as its object an ordinary noun. A preposition can also have as its object the -ing form know as a gerund. In terms of the GMAT SC, it is illegal to have the construction: [preposition] + [noun] + [-ing form of verb]. For example, in answer choice (A),
...there are few signs of increasing energy prices driving up the cost of other goods so far
We are trying pack action into a prepositional phrase. If we want to describe action, we need a bonafide clause. This is why (A) is wrong.

(C) changes the meaning --- by saying "... few signs of higher energy prices are driving up the cost of other goods..." , it is suggesting that the "signs" are driving up the cost of the other goods. What the original sentence says, and what makes logical sense, is that the "higher energy prices" are driving up these costs. In swapping around the grammatical forms, (C) changes it something that is both different in meaning and illogical. (C) is wrong.

We have rejected the first four answers, so we hope (E) works! Fortunately, it does.
(E) Policy makers remain concerned about the prospect of inflation, despite the dearth of signs thus far that increasing energy prices are driving up the cost of other goods.
The action that (A) tried to cram into a prepositional phrase here appears correctly in a "that" clause with a full bonafide [noun] + [verb] structure: "that increasing energy prices are driving up the cost of other goods.
Everything is correct in this option.

Does all this make sense?

Mike