The correct answer is C. The balance of nature.
The balance of nature is a delicate ecosystem that is easily disrupted by human activity. When animals are killed, it can have a ripple effect on the entire ecosystem. For example, if a predator is killed, the prey population may increase, which can lead to a decrease in the population of the plants that the prey eat. This can then lead to a decrease in the population of the animals that eat those plants, and so on.
Humans have a responsibility to protect the balance of nature. We can do this by reducing our impact on the environment, such as by reducing our consumption of resources and by conserving energy. We can also support organizations that are working to protect wildlife and their habitats.
Option A is incorrect because killing animals is not good for the ecosystem. Option B is incorrect because killing animals is not good for humans. Option D is incorrect because killing animals does disturb the balance of nature.