Question

Which of the following describes an allele whose characteristic phenotype is masked by the presence of a second, different allele?

Answer 1

The allele that can mask the presence of another allele is called dominant. The allele that is masked is recessive and if both alleles can be detected in the phenotype, then they are codominant. If they produce an intermediate phenotype like pink instead of red or white, then they have a relationship of incomplete dominance.

Answer 2

This is called a recessive allele. 
On the other hand, dominant alleles are the ones that show in the phenotype of an organism.