Among the following, which one is not an ape?

The correct answer is C because Langurs are classified as monkeys, not apes. Biological classification divides primates into different groups. Apes, which include Gibbons known as lesser apes and Gorillas, Orangutans, and Chimpanzees known as great apes, are characterized by the absence of a tail and larger brain-to-body size ratios. In contrast, Langurs belong to the family of Old World monkeys. The most visible physical difference is that Langurs possess a long tail, which is a defining feature of monkeys that distinguishes them from apes. Therefore, while Gibbons, Gorillas, and Orangutans are all apes, the Langur is a monkey.