Answer:
B. half, half
Explanation:
When a diploid organism has one dominant allele and one recessive allele of a gene, it is said to be heterozygous for the gene. During gamete formation, random segregation of homologous chromosomes leads to separation and random distribution of alleles of a gene in separate gametes. Therefore, a heterozygous individual for a gene forms two types of gametes: 50% of the gametes with dominant allele and rest 50% with the recessive allele.
For instance, an individual with an "Aa" genotype will form 50% gametes with an "A" allele and 50% gametes with an "a" allele.