The answer is Deer. Monogamy refers to a mating system in which one male and one female mate and form a long-term bond. Among the given options, only Deer has a monogamous mating system, where a male and female deer form a bond and stay together for a period of time, sometimes for life. Wolves, Walruses, and Seals are known to be polygamous, where males mate with multiple females, and females mate with multiple males.