This is a tough question, especially between option (B), (C) and (E). I ended up choosing
(B) after spending 02:55.
Firstly, we can eliminate (A) and (D) because "since the advent of quantum mechanics began" is either redundant or nonsensical. It is all right to say
"since the advent of quantum mechanics" or "since quantum mechanics began" but not "since the advent of quantum mechanics began".
Next, I feel that (C) changes the intended meaning by moving "Since the advent of quantum mechanics" to the very beginning of the sentence. Now, "Since the advent of quantum mechanics" modifies "it is true". The differences may be subtle but exist nevertheless.
Finally, both (B) and (E) are grammatically sound. Sentence structure of (E), Subordinate clause + Main clause, is much more common than that of (B), Main clause + absolute construction.
But (E) introduces a contrast between "being the most powerful tools" and "forcing some rather pointed and profound questions about humanity as a species". We have to wonder if such contrast exists. Do we see any contrast between the two functions?
Ultimately, we have to make the judgement call whether "forcing some rather pointed and profound questions about humanity as a species" is a positive thing? If Yes, "although" is unjustified. (Everyone should agree that "being the most powerful tools" is positive.)
Because I actually welcome the opportunity to answer "rather pointed and profound questions about humanity as a species", I eliminated (E).