In Mice, Short Hair Is Dominant to Long Hair

Multiple Choice

In mice, short hair is dominant to long hair. If a short-haired individual is crossed with a long-haired individual and both long- and short-haired offspring result, one can conclude that

A) the short-haired individual is homozygous.
B) the short-haired individual is heterozygous.
C) the long-haired individual is homozygous.
D) the long-haired individual is heterozygous.
E) This cannot be answered without more information.