How is cross-fertilization advantageous over asexual reproduction?

Cross-fertilization is the binding of female and male gametes or the sex cells from two different individuals given they are of the same species. On the other hand, asexual reproduction involves the formation of offspring only from a single individual where a cell only makes a copy of itself. It is advantageous since it would introduce diversity to a species which would help it to be more resistant to any factors that could damage it like diseases. 

The answer will be d