Choose the sentence that uses parallel structure correctly.

• A. He likes swimming, running, and bicycling.
• B. He likes swimming, running, and to bicycle.
• C. He likes swimming, running, and bicycles.
• D. He likes to swim, running, and bicycling.

Answer: (A)

Parallel structure means the parts of a list share the same grammatical form, so the sentence reads evenly and clearly. In this sentence, the ideas after the verb likes should all be in the same form. The best choice keeps swimming, running, and bicycling all as -ing forms (gerunds) that act like nouns and serve as the objects of likes. This consistency makes the sentence smooth and balanced.

The other options disrupt that pattern. One uses an infinitive form (to bicycle) where the others are gerunds, which breaks the parallelism. Another uses a noun (bicycles) instead of an action form, also breaking the pattern. Another mixes an infinitive (to swim) with gerunds (running and bicycling), which again fails to maintain the same grammatical form throughout the list.