Previously, it was thought that the blending hypothesis explained inheritance. The blending hypothesis maintained that __________.

A. the characters governed by genes in the egg are different from the characters governed by genes in the sperm
B. many genes are lost in their transmission to offspring, but the remaining genes gradually reproduce the lost genes
C. mutation is the major source of new gene combinations
D. after a mating, genes of the two parents are mixed in the offspring and lose their individual identities