Video Explanation

Text Explanation

Usual suspects

Parallelism

There is some mighty complex parallelism going on here since we need to juggle two elements: “suggest that” and “either…or”. See each answer choice below.

Subject-verb agreement

The noun “fossils” should take “suggest”, not “suggests”. Unfortunately, noticing this only helps get rid of (E).

Not-so-usual suspects

Idiom: Yet TO BE “participle-ed”

This describes something that has yet to happen. We can eliminate (B) and (E).

(A) To simply the parallel clauses: suggest that NOUN PHRASE is EITHER adj. OR

At this point, immediately after the OR we would need an adjective. Instead we get a new relative clause starting with “that”. Clear violation of parallelism.

(B) attributed should be “to be attributed”. (See “not-so-usual suspects”).

(C) Same parallelism issues as (A). Further, "suggest" is a verb that idiomatically requires "that" to follow it. (See this blog post for more on this.) Since (C) loses that construction, we can't choose it.

(D) moves the “either” right before the “that” and directly after “suggest”. This juxtaposition allows for parallelism between the two “that” clauses. Notice the part that comes right after the first “that”, “our classification of extinct species is deficient” is parallel the noun phrase that comes after the second “that”, “our method of identification is lacking”.

Absolute phrase alert: “many unclassified species meriting distinct branches.” This phrase modifies the entire preceding clause, or elaborates on it. The absolute phrase is a fragment that usually contains a participle.

(E) Same as (B).