Question

why is it said that sexual reproduction promotes diversity of characters in the offsprings?

Answer 1

It is due to :
# Crossing over
# Randomly any chromosome from the homologous pair can get transferred in Gametes (independent of another pair )
# Random fusion between gametes. and also
#Random mating between members of the same species.

Answer 2

Answer:

It is because sexual reproduction results from the fusion of two gametes coming from two different and sexual distinct individuals , this leads to variation which is necessary for evolution.