IMO : B for following reason/s:
1. The underlined start with no subject and the subject of underlined part is "the time.. and the distance" that is plural so verb has to be plural.

so we are down to B ,C and D
In D
"how long .." and "the distance" are not parallel.

In C
1. The time in which seems to define a specific time.
2. "No less" is different from "equal" as adjective.

IMO B.

SV agreement for the second clause should be plural 'are' as it speaking about two things - A/E are out.

C - time in which is wrong, not parallel.
D - how long it takes to fabricate, not parallel.

karthikpandian19 wrote:While the relative costs of concrete and steel are a predominant consideration in the design of a skyscraper, of no less importance to civil engineers is the time needed to fabricate the structural elements and the distance of the project site from the production sites of the raw materials.

of no less importance to civil engineers is the time needed to fabricate the structural elements
of no less importance to civil engineers are the time needed to fabricate the structural elements
of equal civil-engineering importance are the time in which the structural elements are fabricated
for a civil engineer, of no less importance are how long it takes to fabricate the structural elements
of equal importance to a civil engineer is the amount of time needed for fabricating the structural elements

edited: should be B
as explained by previous user
user123321

OA is B

What helps us identify this question as a Subject Verb Agreement question as well as identify the mistake are the following Stop Signs:verb precedes subject and plural subject built of singular nouns connected by and

A. Incorrect.This answer choice is grammatically incorrect. The singular verb is does not agree with the plural subject the time needed...and the distance, etc.What helps us identify this question as a Subject Verb Agreement question as well as identify the mistake are the following Stop Signs:verb precedes subject and plural subject built of singular nouns connected by and

B. This answer choice corrects the Subject Verb Agreement mistake in the original question by changing the singular verb is to the plural verb are.What helps us identify this question as a Subject Verb Agreement question as well as identify the mistake are the following Stop Signs:verb precedes subject and plural subject built of singular nouns connected by and

C. While this answer choice corrects the Subject Verb Agreement mistake in the original question by changing the singular verb is to the plural verb are, it is stylistically flawed.The phrase civil-engineering importance is awkward and changes the meaning of the original sentence. The importance of an issue for the professionals - civil engineers - may be different from the importance of the issue for the profession or discipline of civil-engineering.Also, the phrase in which the structural elements are fabricated is stylistically inferior because it unnecessarily changes the noun phrase time needed for the fabrication, etc. into a passive sentence.What helps us identify this question as a Subject Verb Agreement question as well as identify the mistake are the following Stop Signs:verb precedes subject and plural subject built of singular nouns connected by and

D. ncorrect.While this answer choice corrects the Subject Verb Agreement mistake in the original sentence, by changing the singular verb is to the plural verb are, it introduces a Parallelism mistake which makes it grammatically incorrect. The construction A and B requires that A and B belong to the same part of speech. In this answer choice, B is a noun (distance) whereas A is a complete sentence (how long it takes).What helps us identify this question as a Subject Verb Agreement question as well as identify the mistake are the following Stop Signs:verb precedes subject and plural subject built of singular nouns connected by and

E. This answer choice repeats the Subject Verb Agreement mistake in the original sentence. The singular verb is does not agree with the plural subject the amount of time needed...and the distance, etc.What helps us identify this question as a Subject Verb Agreement question as well as identify the mistake are the following Stop Signs:verb precedes subject and plural subject built of singular nouns connected by and. In addition, the phrase amount of time needed in the corrected sentence is redundant. It is not necessary to use the words amount of -- the phrase time needed expresses the same meaning.