It makes sense that a human with excessive body odor may have trouble convincing other people to date them. Beyond that, most people probably do not think that smell is a major factor in deciding whom to date or with whom have children.
However, evidence suggests that there is a connection between personal odor and immune genes. Studies indicate that humans prefer the odor of individuals whose immune system genes are different than their own.
Which of the following could be the evolutionary benefit of people with different immune system alleles mating?