Answer:
A gamete is haploid (1N) so 'Aa' & 'AA' are diploid and during cell division (mitosis) gametes are formed and then 2 gametes merge together to make a diploid (think of sperm and egg, each is haploid or 1N, when fertilization occurs the egg and sperm form 1 cell that is 2N or diploid).
So the possible gametes for 'Aa' would be 'A' & 'a' while for 'AA' the only gametes possible are 'A'
If the question is asking what the possible gametes are for 'AaBB' the haploid (gamete) can be 'AB' or 'aB'