Answer:
a) is.
Step-by-step explanation:
Just try out the options!
He are my brother does not sound right. Are would only work if there is a second person involved.
He am my brother is not correct. Nothing could make this sentence work.
I'm not sure but I'm going to guess that 'wete' is supposed to be were. In either case, this isn't right.
So it's is. Hope this was helpful!