Identify the sentence that uses incorrect parallel structure.

A. Strengthening core muscles, icing regularly, and visiting the chiropractor can all help reduce back pain.
B. Mom is watching TV in the living room, and Dad is mowing the backyard.
C. I usually like to unwind with a book or fall asleep in my beach chair.
D. Concerned citizens can write letters, show up at the polls, and will be wearing pins that say, "Honesty Now."