Final answer:
The appropriate form of the verb 'hacer' to fill in the blank is 'hizo'.
Step-by-step explanation:
The appropriate form of the verb 'hacer' to fill in the blank in the sentence is C. hizo.
The sentence 'todo lo posible para ayudar a Ana' translates to 'did everything possible to help Ana' in English. The verb 'hizo' is the third-person singular preterite form of 'hacer', which means 'to do' or 'to make'.
For example, if the sentence was 'Yo __ todo lo posible para ayudar a Ana', you would use the first-person singular form 'hice'.
Learn more about Spanish verb conjugation