Final answer:
The most common mating system among primates is polygynous, where one male mates with multiple females. There are also polyandrous and monogamous mating systems seen in certain primate species.
Step-by-step explanation:
The most common mating system among primates is polygynous, which means one male mates with multiple females. This mating system is observed in species such as chimpanzees, where a dominant male mates with several females in his group. Another mating system seen in some primates is polyandrous, where one female mates with multiple males. This is seen in certain primate species like marmosets. Lastly, there is also the monogamous mating system, where one male mates with one female and they stay together for at least one breeding season. This is observed in some primate species, including certain bird populations.