Review the sentence:
To protect her delicate hands, Fran will not rake the yard, do the dishes,
or __________.
The blank requires a future tense verb. You chose won't scrub the bathtub, which contains too many words, causing a parallelism error. Since the second item in the series, do, drops the will not (the words are understood to be there), the third item must do the same.
Before you continue, review the rules for parallel structure.