Question

The longer the chromosomes of an organism,the more genetic variability it gets from :
1) Independent assortment
2) Linkage
3) Crossing over
4) Mutation

Answer 1

The longer the chromosomes of an organism,the more genetic variability it gets from Crossing over.

In Crossing over there is exchange of genetic material by the homologous chromosomes, resulting in recombinant chromosomes while sexual reproduction.