Which sentence has an awkward shift in voice?

A. We practiced for the debate and many arguments were rehearsed.

B. We practiced for the debate and we heard many arguments.

C. The debate was rehearsed and many arguments were heard.

D. As we practiced for the debate we rehearsed many arguments.

The correct answer is A. We practiced for the debate and many arguments were rehearsed.

As you can see in this sentence, in the first part the pronoun we is used, and in the latter part, that pronoun just disappears and the sentence suddenly becomes passive rather than active. The shift isn't done properly - it is rather awkward. The other options are consistent - they use only one voice rather than two (like in sentence A).