Question

an allele is:
the genes that determine a persons gender
a gene only found in females
parts of dna that do not code for a protein
a variation of a gene

Explanation:

An allele is a variation of a gene. Genes are segments of DNA that code for specific traits. Alleles are different forms of the same gene. For example, for the gene that determines eye color, there are alleles for blue, brown, green, etc. The option "The genes that determine a person’s gender" refers to sex - determining genes (like the SRY gene on the Y - chromosome for male development). The option "A gene only found in females" is incorrect as alleles are not gender - exclusive in that sense. The option "Parts of DNA that do not code for a protein" is incorrect as alleles are part of coding regions (genes) which can code for proteins.

Answer:

A variation of a gene.