OA should be E.
they cannot be used for the State Assembly. Its the assemblymen who will agree or not.
Agree on is the correct idiom. So, E should be the answer.

The original sentence contains a pronoun error. The pronoun "they" requires a plural
antecedent though there is none in the sentence; "State Assembly" is singular and
"they" cannot be used to refer to the politicians collectively since they were not
mentioned in the sentence.
(A) This choice is incorrect as it repeats the original sentence.
(B) The pronoun "they" is incorrect here because there is no plural antecedent.
Moreover, the phrase "agree about" is unidiomatic; "agree on" should be used
instead.
(C) The singular pronoun "it" correctly refers to the singular noun "the State
Assembly." However, the phrase "agree about" is unidiomatic; "agree on" should be
used instead.
(D) The use of "the Assemblymen" instead of "they" corrects the original pronoun
problem by eliminating the pronoun "they" altogether. However, the phrase "agree
about" is unidiomatic; "agree on" should be used instead.
(E) CORRECT. The use of "the Assemblymen" instead of "they" corrects the original
pronoun problem by eliminating the pronoun "they" altogether.
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Correct Answer must be (E) for the highlighted errors in other options...
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