In addition to her work on the Miocene hominid fossil record, Mary
Leakey contributed to archaeology with her discovery of the earliest direct evidence of hominid activity and painstakingly documenting East African cave paintings.
Option Elimination -
"her" can refer to Mary Leaky (noun) or Mary Leaky's (noun in possessive case) - Eliminating the options here just because we may be less familiar with possessive pronouns referring to a noun in possessive case is not the right strategy here. At best, it is a red herring. We have to overcome this barrier to look for other issues to eliminate the options.
(A) Leakey contributed to archaeology with her discovery of the earliest direct evidence of hominid activity and painstakingly documenting - "And" demands parallelism. On the left side of "and," we have a prepositional phrase "with her discovery," and on the right side, we have a gerund "painstakingly documenting" - not parallel.
(B) Leakey contributed to archaeology by her discovery of the earliest direct evidence of hominid activity and by painstakingly documenting - There is nothing grammatically wrong with this option: "discovery" - noun can be parallel to "documenting." Here is an example - Doctors generally agree that such factors as cigarette smoking, eating rich foods high in fats, and alcohol consumption not only do damage by themselves but also aggravate genetic predispositions toward certain diseases.
Here, three factors - smoking (gerund), eating (gerund), and consumption (noun) are perfectly parallel. So Noun can be parallel to Noun can be parallel to ING OF can be parallel to ING. BUT the preference is N>ING of >ING. Now, between B and D (that we'll discuss), we have noun versus noun parallelism as against noun versus ING parallelism here in B, and based on the preference, any option with the noun versus noun parallelism is preferred over others. Again, there is nothing wrong with this option - it's just that between B and D - D is preferred. And if you got this question wrong, it's not the end of the world; keep practicing.
(C) Leakey was a contributor to archaeology with her discovery of the earliest direct evidence of hominid activity and with her painstaking documentation of - Leaky contributed is preferred over Leaky was a contributor.
(D) Leakey’s contributions to archaeology include her discovery of the earliest direct evidence of hominid activity and her painstaking documentation of - contributions (subject) and plural verb (include). "her discovery" - noun parallel to "painstaking (adjective) documentation" - noun. Perfect. But in order to reach this option and keep it, we have to expand our knowledge that passive pronouns can refer to nouns (we know) but also nouns in the possessive case.
(E) Leakey’s contributions to archaeology include her discovering the earliest direct evidence of hominid activity and painstaking documentation of - discovering (gerund) and on the other side of and we have documentation (noun) if you are looking at "painstaking," its an adjective. Again, as we discussed in B, construction in option D is a preferred one over others.
Now let's look at the 2nd version of the sentence to consolidate our learnings.
In addition to her work on the Miocene hominid fossil,
Mary Leakey contributed to archaeology through her discovery of the earliest direct evidence of hominid activity and through her painstaking documentation of East African cave paintings.
A) Mary Leakey contributed to archaeology through her discovery of the earliest direct evidence of hominid activity and through her painstaking documentation of - the prepositional phrase "through her discovery (noun)" is parallel to the prepositional phrase "through her painstaking documentation (noun)." Moreover, a noun is parallel to a noun.
B) Mary Leakey contributed to archaeology by her discovery of the earliest direct evidence of hominid activity and painstakingly documenting - noun (discovery) and gerund (painstakingly documenting)
C) Mary Leakey was a contributor to archaeology by discovering the earliest direct evidence of hominid activity and with her painstaking documentation of -same as we discussed for C above.
D) Mary Leakey's contributions to archaeology include her discovery of the earliest direct evidence of hominid activity and painstakingly documenting - discovery (noun) and documenting (gerund) preference, as we discussed above. In option A, a noun parallel to a noun is preferred.
E) Mary Leakey's contributions to archaeology include her discovering the earliest direct evidence of hominid activity and painstaking documentation of -Same as we discussed in E above.