Answer:
Anything you see physically on an organism can be considered as an allele.
Step-by-step explanation:
An allele is one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Let's use one example: a white bunny with red eyes. One allele for this animal would be that it has white fur color. Another allele would be its red eye color.
Let's use another example, but with two people. Person A has straight hair and freckles. Person B has curly hair and no freckles. Person A's alleles would be straight hair and freckles. Person B's alleles would be curly hair and no freckles.
Any physical characteristic trait on an organism can be considered as an allele for that organism.