Hi kanika123,

What is the source of this question?

I ask because the GMAT format for SCs is to have answer A match the original prompt (in this example, it's answer E that matches the original prompt).

In regards to the grammar, this SC uses 2-part parallelism. Since the second part uses the word "partly", the first part would need to use "partly" also.
Eliminate C and E

Next, I'd look at the "style" of the sentence:
-Answer B sounds clunky ("partly because of their steers acquiring")
-Answer D also sounds clunky and is passive ("partly because certain characteristics should be acquired BY")

Answer A is parallel in both the word "partly" and in the "to *verb*" (to acquire....to provide) phrase.

GMAT assassins aren't born, they're made,
Rich