Polydactyly (Extra Fingers or Toes) in Humans Is Inherited as an Autosomal

Multiple Choice

Polydactyly (extra fingers or toes) in humans is inherited as an autosomal dominant trait. Some heterozygotes, however, do not have any visible abnormality. This situation could result from

A) a reduced level of penetrance.
B) reduced expressivity.
C) incomplete dominance.
D) polygenic inheritance.
E) phenotypic variability