SC--Neuroscientists and their knowledge

[rx_11]

Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are
(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(D) Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood,
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood






OA is A

But why D & E are wrong?

The OE says :

D The final descriptor in present tense, now drawing conclusions ... does not fit the opening clause, which is in present-perfect tense (have amassed a wealth ...) and seems to modify adulthood.

E Like D, this sentence attempts to attach a present-tense descriptor to a present-perfect
clause.


What does it mean:"not fit the opening clause"? Should we use "now having drawn"??? Moreover, why the final descriptor seems to modify adulthood? I think participle(drawing) always modify the verb of the main clause.. Why it would seem to modify a noun??

[elevinty]

am with you in this problem.
Can someone please shed some light into this.

*this is OG question 12ed

[kbhardwaj]

Here is my understanding.

For option D: The working verb is "have amassed". This makes the first part (about amassing knowledge) an independent sentence. The problem it creates is that we cannot find a subject for the verb "are" in the second part (about drawing conclusions).

For option E: Again the working verb is "have amassed". This makes the first part (about amassing knowledge) an independent sentence. In this case there is no comma, so "its development" becomes the subject of the verb "are" which clearly does not make sense as development cannot draw conclusions.