Which of the following adaptations is most beneficial for animals living on land?

The presence of an exoskeleton provides significant advantages for animals living on land. This hard outer covering serves multiple purposes that are crucial for terrestrial life. Firstly, it offers protection against physical injury and predation, which is particularly important in terrestrial environments where there is increased risk from predators and environmental hazards.

Moreover, an exoskeleton plays a critical role in preventing desiccation, or drying out, which is a common challenge for land-dwelling organisms. By providing a barrier against water loss, an exoskeleton helps to maintain internal hydration levels, allowing these animals to thrive in various land environments.

Additionally, exoskeletons contribute to structural support, enabling animals to maintain their shape and withstand the force of gravity more effectively compared to soft-bodied organisms, which may struggle with structural integrity on land.

While other adaptations, like a notochord and dorsal nerve cord or the ability to undergo metamorphosis, are important in different ecological contexts, they do not specifically address the unique challenges posed by a terrestrial lifestyle as directly as an exoskeleton does. An open circulatory system has its own benefits in certain contexts, but it is primarily associated with aquatic organisms and is less suited to the demands of life on land.