Answer:
C. The awkward phrasing clouds the fact that the speaker wants one volunteer to do both tasks.
Explanation:
The correct would be ''Which one of you will help do the dishes and take out the trash?'' If it is written like this, it won't be awkward because the speaker is talking to both volunteers in the sentence asking them who wants to do the tasks.
When we are fixing an error in parallel structure, we must put the words in it from the same series or phrases. When we put everything in the same form, the readers will understand the sentence and the sentence will be much easier for reading. With the same form, sentences are making the essays or paragraphs smoothly and easy for reading.