Biologists have encountered a new species of giant squid, one that the

Choice (E) is more concise than other choices with 'that they'.

The Non-underlined sentence already has a pronoun ONE, It is incorrect to use another
A. that they believe is
B. that they believe it to be
C. they believe it is of
D. they believe that is
E. they believe to be of

Marked E based on meaning as "to be" is required .
Can anyone explain the elimination for C and D ?

Hi dream21,

Underlined pronouns are a classic sign of possible pronoun errors, so check for proper pronoun usage. In this case, the pronoun "they" is preceded by only one plural noun, so its usage is correct.
So, we don't need "that" since it has already been conveyed by "one".
Eliminate choices A and B.

Of the remaining choices, choice (C) uses the awkward-sounding and unnecessary "it," and (D) does the same with "that."
Only Answer Choice (E) sounds correct and is the correct answer.

Happy to help you.

"Kudos" if you like the post.

Believe to be of is correct usage and the other , errors in other options are highlighted in red.

So, Correct answer must be (E)

Even though I agree with the official answer, I do not believe that the pronoun “that” is incorrect here, as many experts say. One member just eliminates the options with “that” without an explanation. Another states-“ the non-underlined sentence already has a pronoun ONE, it is incorrect to use another”; nevertheless, I cannot find that rule anywhere.

As I see it, the pronoun “one”, which refers to “a new species”, introduces an absolute phrase; “one” is then modified by the relative clause “that they believe to be of a type heretofore unknown to science.”

“That” refers to “one”, which in turn refers to “a new species” – “they believe this new species to be of…”

So the pronoun “that” introduces the relative clause and is not incorrect. On the other hand, the pronoun can be omitted because it is not the subject of the relative clause. The fact that we can omit “that” does not make the choices that use this pronoun wrong.

So we can eliminate A, C, and D because the idiom is incorrect –believe to be.
We eliminate B because the pronoun “it” is redundant: the pronoun “it” refers to “a new species”, but the pronoun “that” has already replaced this phrase.

Went with D instead of E. "That" I thought was correctly referring to "Species".
I read somewhere that "to be" is passive.
isnt it?

E is the right choice as that, they and it all point to one and are redundant. Also believe to be is the right idiom.

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