Final answer:
The correct verb form to complete the question is "parle-t-il"
Step-by-step explanation:
The correct verb form to complete the question "Pierre parle espagnol?" is C. parle-t-il.
This form is used to invert the subject and the verb in a yes/no question in French. It is formed by placing the subject pronoun (in this case, "il") after the verb (in this case, "parle"), and adding a hyphen between them.
For example, the sentence "Il parle espagnol" (He speaks Spanish) becomes the question "Parle-t-il espagnol?" (Does he speak Spanish?).
Learn more about Selecting the correct verb form in French