Final answer:
The correct choice to change the sentence from passive voice to active voice is 'The gorilla ate the banana'.
Step-by-step explanation:
To change the sentence 'The banana was eaten by the boy' from passive voice to active voice, we need to make the subject of the sentence perform the action. The correct choice is '2) The gorilla ate the banana'. In this sentence, the subject 'gorilla' is performing the action 'ate' on the object 'banana'.