Question

which sentence contains a split infinitive?
it is important to wear plenty of sunscreen at an outdoor swim meet.
the coach tells the swimmers how to improve their performance.
parents drive to the local swim club so they can watch the competition.
swimmers must be sure to completely follow all of the team guidelines.

Explanation:

A split infinitive occurs when an adverb is placed between the "to" and the base form of a verb. In the last option, the adverb "completely" separates "to" and "follow", creating a split infinitive. The other sentences keep "to" and the verb base form together without an intervening adverb.

Answer:

D. Swimmers must be sure to completely follow all of the team guidelines.