Find the part of the sentence that contains an error:
What the committee failed to deliberate on adequately (1)/ were not the policy’s objectives themselves, (2)/ but the political ramifications it (3)/ might have had if implemented without broader consensus. (4)

Correct option is B

Option (2) contains an error.
Detailed explanation of error:
The subject of the sentence is the singular noun clause: “What the committee failed to deliberate on adequately”. A “what-clause” functions as a singular subject, so it should take a singular verb. Therefore, “were” is incorrect; it should be “was.”
Correct sentence: What the committee failed to deliberate on adequately was not the policy’s objectives themselves, but the political ramifications it might have had…
Grammatical rule used: Subject–Verb Agreement (Noun Clause as Singular Subject)
· A clause beginning with what/that/whether used as a subject is treated as singular → takes was/is/has, not were/are/have.
· Example (rule used):
· Correct: What he said was surprising.
· Incorrect: What he said were surprising.
· Information booster / exception:
· Even if the complement after the verb is plural (e.g., “the reasons”), the verb still agrees with the subject clause: What mattered was the reasons behind it.