Final answer:
The form of natural selection that leads to an increase in the frequency of alleles which promote the fitness of genetic relatives is called kin selection. The correct option is D.
Step-by-step explanation:
This type of selection explains behaviors in animals that may seem altruistic or self-sacrificing. For example, an animal may risk its own life to save its relatives because in doing so, it ensures that the genes they share, a proportion of which will be identical, are passed on to the next generation.
Kin selection is a significant aspect of adaptive evolution, where the increase in frequency of beneficial alleles and decrease in deleterious alleles occur due to selection processes. This is different from stabilizing selection which acts to decrease genetic variance by favoring an average phenotype, or directional selection which shifts allele frequencies in a consistent direction, favoring either an increase or decrease in the value of a specific trait.
Hence, D is the correct option.