Question

To tell someone to turn we would use the infinitive verb ---.

Answer 1

Gira - means to tour not turn 
you would say girar

Answer 2

Answer: The right answer is "girar."

Explanation: Just to elaborate a little on the answer, it can also be added that the verb "girar"—and also the verbs "voltear," "virar," or "torcer," which can be used as synonyms—is the one you would use to ask someone to turn in Spanish. You might say "gira" (second person singular) or "giren" (second person plural), for instance.