Correct answer: D
A pollen is where male gametes are produced and so the number of chromosomes, as we are talking about gametes, is n. This means that the grain of pollen will only have a copy of each gene, and therefore only one allele for each gene - one S, and one T or t. So, the possible combinations are ST and St.
I am taking the test right no and I picked the answer C. But I am not 100% sure that it is the correct answer. It just seems to be the one that makes the most sense.
