hard writing question

As a delegate to the United Nations General Assembly in 1946, (Eleanor Roosevelt and Andrey Vyshinsky debated) the importance of free speech.
A.Eleanor Roosevelt and Andrey Vyshinsky debated
B.Eleanor Roosevelt and Andrey Vyshinsky debated over
C.Eleanor Roosevelt and Andrey Vyshinsky, they debated
D.Eleanor Roosevelt debated Andrey Vyshinsky over
E.Eleanor Roosevelt, who debated Andrey Vyshinsky over

i choose B and the answer is D
thx for the helpers

“a delegate” is singular, so it cannot match any of the “and” choices; E is ungrammatical; and the only valid option is D.

thx i didn’t notice it was singular