Final answer:
In complete dominance, the recessive allele is not expressed in a heterozygous individual, while the dominant allele is expressed.A dominant allele
Step-by-step explanation:
In a trait showing complete dominance, the allele that is NOT expressed in the heterozygous individual is the B) Recessive allele. A dominant allele will mask the presence of a recessive allele in the phenotype of the heterozygous genotype, so the recessive trait only appears when an individual is homozygous recessive (when they have two copies of the recessive allele).