Final answer:
The correct option to fill in the blanks is A) 'won; has not been,' which fits the past tense and the present perfect tense needed for the sentence.
The correct sentence is A) won; is.
Step-by-step explanation:
The correct form of the verbs to complete the sentence 'Several months ago, he (win) a big prize in a lottery, and he (not be) the same person since' would be:
'Several months ago, he won a big prize in a lottery, and he has not been the same person since.'
This means the correct option is A) won; has not been. The verb 'won' is the past tense of 'win,' which is appropriate because the action happened several months ago. The phrase 'has not been' is the present perfect tense of 'be,' indicating a change that occurred in the past and continues to the present.