Why do cells used in sexual reproduction need to have fewer chromosomes?

Question

to increase diversity by creating new chromosomes from scratch
to maintain the number of chromosomes specific to the species
to decrease the number of chromosomes in the next generation
to eliminate the chromosomes that prevent asexual reproduction

Answer 1

I don't know if it requires fewer chromosomes, but sexual reproduction does maintain the number of chromosomes specific to the species.

Answer 2

B. to maintain the number of chromosomes specific to the species is correct!!! I took the test :D