A new cancer drug, whose development depends on various scientific advances in molecular chemistry and neuroscience, is expected to be available to general public in the next two decades.
The intended meaning of this sentence is to convey that the new drug is expected to be available at some time in the future.
In (B), (C), and (D), the meaning of the sentence changes - In these options, it is the "development" that is expected to be available in the future, not the new drug itself; this does not make any sense at all. Hence, we can
eliminate (B), (C), and (D).
What we are now left with are (A) and (E)
A )
A new cancer drug, whose development depends on various scientific advances in molecular chemistry and neuroscience, is expected to be available to general public in the next two decades. - (A) has no error in it. Hence,
(A) is the right answer choice.E)
A new cancer drug, with its development dependent on various scientific advances in molecular chemistry and neuroscience, is expected to be available to general public in the next two decades. - even though the prepositional phrase "with its development......" correctly modifies the subject "new drug", there's a meaning ambiguity here.
This structure effectively conveys that The new drug produces an effect that is replicated by the prepositional phrase. This does not make sense since a prepositional phrase itself cannot replicate any action. To help you understand this situation a bit better, let us draw a parallel example:
John, with his skill to jump over fences, was able to escape from the neighbor's vicious rottweiler. - the meaning here is that both 'John' and "John's ability" was able to escape from the rottweiler; This obviously won't make any sense.
Similarly, the structure introduced in (E) does not make any sense. Hence, we can
eliminate (E).If you find this explanation helpful, please do give it a kudos