Check these lines, lathlee:
as history has progressed, they have been revealed as products of their era, possessing inherent explanatory limitations, rather than the universal truths they purported to be.
That's describing the problems with those grand theories, the mistakes they made.
Here's my prephrase for this question:
"Some old theories, problems with them, nostalgia, possibility for a change."
Answer C is imperfect in that it is incomplete, but it doesn't introduce anything new that wasn't part of my prephrase, so it's not awful. I'll keep it as a contender.
Another way to approach these questions is to eliminate answers that don't follow from the facts of the passage. That gets rid of answer A (no example showing their accuracy), answer B (no defense of the theories), answer D (no speculation regarding their future), and answer E (no discussion of the differences between them).
Always start with your prephrase, then sort losers and contenders, then pick the best answer from among the contenders. Never let yourself get hung up on finding perfect answers! Don't waste time trying to pick apart an answer that is clearly better than the others!
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
Follow me on Twitter at
https://twitter.com/LSATadam