A.It should be " Were good grammar, vocabulary, voice inflection used?" because the subject (grammar, vocabulary, inflection) is plural.
In statements the subject normally comes before the verb. In questions that order is reversed with the verb coming before the subject.
To test the subject/verb agreement in a question, you can turn it into a statement:
Good grammar, vocabulary, and voice inflection (was/were) used.
In that statement we can see the plural (were) seems right.