SC....confused between two options.

[r2kins]

California is one of the few states in the United States that still has a significant porpoise population, and where this marine animal remains close to the shore.


A
that still has a significant porpoise population, and where
B
that still has a significant porpoise population, where
C
that still has a significant population of porpoises, and where
D
where the population of porpoises is still significant;

E
where there is still a significant population of porpoises and where

OA is E. I feel D is a better option since the semicolon (;) makes the 2'nd part of the sentence into an independent clause. Is parallelism the only reason to choose E?

[cans]

How is OA E?
In E, what does this refers to?? (porpoises is mentioned which is plural)

[avik.ch]

California is one of the few states in the United States that still has a significant porpoise population, and where this marine animal remains close to the shore.


A
that still has a significant porpoise population, and where
B
that still has a significant porpoise population, where
C
that still has a significant population of porpoises, and where
D
where the population of porpoises is still significant;

E
where there is still a significant population of porpoises and where

OA is E. I feel D is a better option since the semicolon (;) makes the 2'nd part of the sentence into an independent clause. Is parallelism the only reason to choose E?

E cannot be the answer as stated above. "this" is singular and it cannot refer to "porpoises".
The only two sentence that uses singular form is A and B ( porpoise). But both uses the form "propoise population". "Propoise population" is the noun here modified by the adjective "significant". So "this" ( in non underlined part) will refer to "propoise population" and not "propoise". So A and B is also wrong.( I am only discussing pronoun ambiguity problem in A and B, there are other problems too )

Is it a OG question ?

Now coming to your query regarding semicolon.
Semicolon is used to connect two closely related independent sentence. In D with semocolon the sentence would be like this .
California is one of the few states in the United States where the population of porpoises is still significant; this marine animal remains close to the shore.
This construction is wrong because ,
1. What is "this" refer to?
2. The two sentence do not seem to be closely related. ( first sentence is quite different from the next )
3. This construction dont satisfy the intended meaning of the sentence as the second part of the sentence doesnt modifies Calofornia.


I hope you find it helpful.

[GmatKiss]

California is one of the few states in the United States that still has a significant porpoise population, and where this marine animal remains close to the shore.


A
that still has a significant porpoise population, and where
B
that still has a significant porpoise population, where
C
that still has a significant population of porpoises, and where
D
where the population of porpoises is still significant; this marine animal (which animal? from where?)
E
where there is still a significant population of porpoises and where

IMO:E is parellel and delivers the proper meaning.

[avik.ch]

California is one of the few states in the United States that still has a significant porpoise population, and where this marine animal remains close to the shore.


A
that still has a significant porpoise population, and where
B
that still has a significant porpoise population, where
C
that still has a significant population of porpoises, and where
D
where the population of porpoises is still significant; this marine animal (which animal? from where?)
E
where there is still a significant population of porpoises and where

IMO:E is parellel and delivers the proper meaning.

In E - How can "this" refer to plural of "porpoises".