The function of sleep theory supported by the illustration is sleep conserves and protects.
From the first sentence, bats sleep a lot because they face little danger from predators and as such, they have a high-calorie diet of insects.
From the second sentence, cows sleep less, because they face more danger from predators and as such, they have a low-calorie diet of insects.
We can conclude that sleep helps to keep animal safe. Therefore, the correct option will be, "Sleep conserves and protects".
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