Among the many reasons for his defeat in the election was his arrogant assumption that his constituents were incapable of understanding economic conditions, and his unwarranted attack on his chief opponent.

A. was his arrogant assumption that his constituents were incapable of understanding economic conditions
B. were his arrogant assumption that his constituents were incapable of understanding economic conditions
C. were his arrogant assumptions that his constituents were incapable of understanding economical conditions
D. were his arrogant assumption that his constituents would be incapable of understanding economics
E. was the arrogant assumption that his constituents was incapable of understanding economic conditions

am not sure whether to take assumption or assumptions as in the former part it is written "among".

viidyasagar wrote:

Among the many reasons for his defeat in the election was his arrogant assumption that his constituents were incapable of understanding economic conditions, and his unwarranted attack on his chief opponent.

A. was his arrogant assumption that his constituents were incapable of understanding economic conditions
B. were his arrogant assumption that his constituents were incapable of understanding economic conditions
C. were his arrogant assumptions that his constituents were incapable of understanding economical conditions
D. were his arrogant assumption that his constituents would be incapable of understanding economics
E. was the arrogant assumption that his constituents was incapable of understanding economic conditions

my answer is B

Concept tested - was vs. were, assumption vs. assumptions

A. was his arrogant assumption that his constituents were incapable of understanding economic conditions - since the non-underlined part contains "many reasons", "were" is a must. Eliminate A and E

D - contains a "would be" about an action that has already taken place. would is wrong

B and C are close

am not sure whether to take assumption or assumptions as in the former part it is written "among".

He has made only one assumption, viz., his constituents were incapable of understanding economic conditions, hence plural "assumptions" is unnecessary.

The plural "Were" refers to the 2 reasons of his defeat.....1. incorrect assumption and 2. unwarranted attack

I go with B

Source please!!!