Solution:
Remember that by definition, alleles are alternative variants of a gene, that is, different sequences of a gene. Now, the genotype refers to these sequences or the Allele that is present at a given locus. These alleles generate a phenotype, which is the observable expression of a genotype, in this case, Red Eyes or White Eyes (depending on the parental cross). According to this, we can conclude that the correct answer is:
Gene can have different forms called alleles.