In a genetic cross involving codominant alleles, what is the key difference between a heterozygous individual and a homozygous individual?

A
Heterozygous individuals have two different alleles for the same gene, while homozygous individuals have two identical alleles.
B
Heterozygous individuals have two identical alleles for the same gene, while homozygous individuals have two different alleles.
C
Heterozygous individuals display the dominant allele phenotype, while homozygous individuals display the recessive allele phenotype.
D
Heterozygous individuals display the recessive allele phenotype, while homozygous individuals display the dominant allele phenotype.

A. Heterozygous individuals have two different alleles for the same gene, while homozygous individuals have two identical alleles.