let us look at each of the answer options -

A - incorrect.
The usage of "being" is redundant. The meaning of the modifier does not change even if "being" is removed from the sentence - "though tiny, blind, and translucent" means the same.
Also, GMAT does not like "being" used as a modifier.

Note that we cannot use plural forms of nouns with articles a and an.
For example - a car (correct). a cars(incorrect).

"a recently discovered species of fish" is singular. this does not agree with the plural pronoun "their".

Also, the meaning of the sentence does not make much sense. the sentence implies that catfish themselves reduce their vulnerability.
It would make more sense to say that thickened bones and armor plates reduced the catfish's vulnerability.

B - Correct answer.
Note that it is not necessary to follow "though" with a clause

C - Incorrect.
the usage of the plural pronoun "their" is incorrect.

the appositive modifier "though tiny, blind, and translucent" refers to "vulnerability".

D - Incorrect.
the usage of the plural pronoun "their" is incorrect.

the usage of the essential modifier "that is tiny, blind, and translucent" changes the meaning of the sentence.
Also, the lack of a contrast indicator "though" changes the meaning of the sentence as well.

E - Incorrect.
this implies that "thickened bones and armor plates" are "tiny, blind, and translucent".
the lack of a contrast indicator "though" changes the meaning of the sentence as well.

NandishSS wrote:Though being tiny, blind, and translucent, a recently discovered species of catfish lessens their vulnerability with thickened bones and armor plates on their sides.

A. Though being tiny, blind, and translucent, a recently discovered species of catfish lessens their vulnerability with thickened bones and armor plates on their sides.

B. Though tiny, blind, and translucent, a recently discovered species of catfish has thickened bones and armor plates on its sides that lessen its vulnerability.

C. A recently discovered species of catfish has thickened bones and armor plates on its sides that lessen their vulnerability, though tiny, blind, and translucent.

D. Thickened bones and armor plates on their sides lessen the vulnerability of a recently discovered species of catfish that is tiny, blind, and translucent.

E. Tiny, blind, and translucent, thickened bones and armor plates on its sides lessen the vulnerability of a recently discovered species of catfish.

In A, C and D, their (plural) does not agree with a recently discovered species (singular).
Eliminate A, C and D.

E: Tiny, blind, and translucent, thickened bones and armor plates
Here, blind seems to refer to thickened bones and armor plates, implying BONES and PLATES can be blind.
This meaning is nonsensical.
Eliminate E.

The correct answer is B.

Isn't species plural...

Sun Light wrote:Isn't species plural...

species can be singular or plural.

Recently A new species WAS discovered.
Here, the article a (which precedes only singular nouns) and the verb was (singular) indicate that species is to be considered SINGULAR.

MANY species ARE being studied.
Here, the quantifier many (which precedes only plural nouns) and the verb are (plural) indicate that species is to be considered PLURAL.

In the SC above, since species is preceded by a, it is to be considered SINGULAR.