If Alleles of Different Genes Always Maintain Their Parental Association

Multiple Choice

If alleles of different genes always maintain their parental association rather than assorting independently into offspring, this is because

A) they are really alleles of a single gene.
B) there was a meiotic error.
C) they are on the same chromosome but far apart.
D) they are very close together on the same chromosome.
E) Mendel's experiments were flawed.