The correct answer is A. When individuals mate with those who are similar to themselves.
Step-by-step explanation
Selective pairing is a tendency of living beings or organisms to mate individuals that same identical of similar characteristics to them. This trend and theory is applicable to any species; however, it has been mostly investigated in humans who are guided by physical characteristics such as height, age, skin color, eyes, hair, among others, or personality traits and emotional traits such as intelligence, attitudes, among others. So, the correct answer is A. When individuals mate with those who are similar to themselves.