In What Way Is Exogamy Adaptive

In what way is exogamy adaptive?

A) It increases the number of individuals that one can rely on in times of need.
B) It increases the likelihood that disadvantageous alleles will find phenotypic expression and thus be eliminated from the population.
C) It impedes peaceful relations among social groups and therefore promotes population expansion.
D) It was an important causal factor in the origin of the state.
E) It reduces the gene pool of a community.