Mendel's law of segregation refers to the fact that each individual has two alleles of the same gene, and these alleles are separated in the formation of the gametes, so each gamete has only 1 allele of each gene.
This means that the two alleles of each gene will be in separate gametes (A and B are true) and that each individual has two alleles of each gene (C is true).
So, the right answer would be D) All of the above