A pleiotropic gene controls multiple traits in an individual. Is a gene evolved during Pliocene. Controls a trait only in combination with another gene. Is expressed only in primitive plants.

Pleiotropy refers to the phenomenon in which a single gene controls several distinct, and seemingly unrelated, phenotypic effects. A classic example of pleiotropy is the human disease PKU (phenylketonuria). This disease can cause mental retardation and reduced hair and skin pigmentation, and can be caused by any of a large number of mutations in a single gene that codes for an enzyme (phenylalanine hydroxylase) that converts the amino acid phenylalanine to tyrosine, another amino acid. So, the correct answer is option A.