Silvia Has Blond Hair,even Though Her Mother and Father Each

Multiple Choice

Silvia has blond hair,even though her mother and father each have brown hair.What do we know about Sylvia's parents?

A) At least one of her parents has a recessive gene for blond hair.
B) Each of her parents must have one recessive gene for blond hair colour.
C) Each of her parents must have one dominant gene for blond hair.
D) Neither of her parents has a gene for blond hair.