Question

He realized that she was crying ______ what he said.

1. A.
   because
2. B.
   because of
3. C.
   as
4. D.
   since

Answer 1

B
Bwhat he said是名词性从句，作介词because of的宾语。because引导原因状语从句，可以说because he said so，as和since也是连词，引导状语从句。