Official Explanation Magoosh:
A question about the Grand Old Man, William Gladstone (1809 – 1898).
Choice (A) commits the famous missing verb mistake, so this is incorrect.
Choice (B) has a modifier mistake: the modifier "opposing government interference to …" touched the noun "classical sense", but that is not what it is supposed to modify. That modifier is supposed to modify the subject, Gladstone, but that's not clear from its position. Also, this choice oddly uses the word "because" as a bridge to the second half, and stating the causality in this way is questionable. Choice (B) is incorrect.
Choice (C) is mostly good, but the second half of the sentence is unnecessarily wordy and indirect. Choice (C) is far from ideal but could pass as correct if we had no better option.
Choice (D) makes a couple strangely wordy and indirect choices: "was opposed to" instead of "opposed," and "were a benefit in democracy" instead of "were beneficial for democracy." These are awkward enough to eliminate (D) as an answer.
Choice (E) is grammatically and logically clear, and states everything with elegance and precision—altogether, much better than (C). Choice (E) is the best answer.