Which of the following statements is true about appearance?
a. The physical appearance of a trait is referred to as the genotype of that trait
b. Alleles of a single gene are always present at different genetic loci
c. The phenotype of the recessive allele is seen in the progeny of a AAX Aa cross
d. The allele presence of a gene refers to the phenotype at that locus
e. The alleles of a single gene are present on homologous chromosomes