Final answer:
The giraffe is the tallest animal on earth due to its long neck adapted for reaching leaves high in trees, whereas the zebra has no such adaptation since it grazes on shorter grass.
Step-by-step explanation:
The tallest animal on earth is the giraffe, not the zebra. Giraffes have specially adapted long necks which allow them to feed on leaves high in trees, reaching heights that other animals cannot. Each cervical vertebra in a full-grown giraffe can be 11 inches tall, and the neck comprises seven vertebrae like most mammals, though they are greatly elongated. This anatomical feature is directly related to their habitat and feeding patterns, where the only available food for them is often on tall trees. Zebras, on the other hand, graze on the African savanna and do not require such elongated necks for survival. Therefore, the correct answer to the question is 'A) Giraffe'. The tallest animal on earth is the giraffe. Giraffes have long necks, which allow them to reach leaves high in trees that other ground animals cannot. An interesting anatomical fact is that almost all mammals have seven cervical vertebrae, regardless of body size. In a full-grown giraffe, each cervical vertebra is 11 inches tall, contributing to their impressive height.