You have been looking at meiosis beginning with a diploid cell that has the genotype AaSs. The alleles in the haploid gametes produced by meiosis are

AS, As, aS, as

Explanation:

Meiosis is the cell division that involves the production of daughter cells or gametes with a reduced number of chromosomes. i.e. diploid (2n) - haploid (n).

According to Gregor Mendel in his law of Segregation, the alleles of a gene will separate into gametes in such a way that only one allele will be present in each sex cell. Hence, in this diploid cell with genotype AaSs, the alleles will separate into the haploid cell in the following genotype proportion:

AS, As, aS, and as