Which sentence has faulty parallelism?

Question

A.
Individual surfboards vary in length, width, and weight.

B.
Top professional surfers use shortboards; amateur surfers usually use longboards.

C.
Surfboards are made of a plastic foam core that is shaped by hand and a shell of fiberglass and resin covers it.

Answer 1

C. Surfboards are made of a plastic foam core that is shaped by hand and a shell of fiberglass and resin covers it.