Which words in the sentence make up the infinitive phrase? To dive to the bottom of the pool, keep your body straight.

a. to the bottom of the pool

b. to dive

c. to dive to the bottom of the pool

d. keep your body straight

The correct answer is C, 'to dive to the bottom of the pool'. The whole first part of the sentence is the infinitive phrase, it cannot be separated so that the correct answers cannot be A or B. And D doesn't have an full infinitive, this is imperative.