Tell me the correct tense for that sentence

tom started his business in spain three months ago. when he returns to italym he (spend) nine months there.

**i'll give you 24 pts for that answer.**

i would need the available options to be listed to give you an answer.

the answer is not b, and i don't think its a, so i choose either man's identity is found within the traditions of his ancestors   or language is a powerful tool, tell me if i was wrong or right by the way