What do alleles show different forms of?

alleles show different forms of a gene.

An allele is a variant form of a gene so the alleles show different forms of a gene. Some genes have a variety of different forms, which are located at the same position, or genetic locus, on a chromosome.

Humans have two alleles at each genetic locus, with one allele inherited from each parent. Example, blood. There are three alleles for blood types in humans A, B and O. In which A and B is co dominant while O is recessive.

In Mice, multiple allele for the coat color. The coat color or hair color in mice is determined by a single gene with a series of alleles. Alleles for black, brown, agouti, gray, albino and other colors of hairs. In which agouti is dominant over black and albino coat color.

what are the options?