Why Does Sexual Reproduction Produce More Genetic Variability in a Population

Why does sexual reproduction produce more genetic variability in a population than asexual reproduction?

A) Organisms arising from sexual reproduction can change their genetic material in response to environmental changes.
B) Offspring are identical to one parent, when produced through sexual reproduction.
C) Sexually reproducing organisms mutate more rapidly during DNA replication than asexually reproducing organisms.
D) Sexually reproducing organisms mix parental genetics in addition to crossing over, random alignment and other modifications.
E) In sexual reproduction, the parents exchange genetic material of the nuclei, thus increasing their variability.