The correct answer is D Heterozygous
Alleles are different variants of the same gene, located at the same place in the genome, the same locus.
Since we have two copies of all of the genes, one inherited from our father and other inherited from our mothers, we have two copies or alleles of the same gene.
If both of our parents pass us the same allele, the same variant of a gene, we would be Homozygous for that gene.
In the case that our parents pass to us two different alleles, we would be Heterozygous.