Which muscle is responsible for controlling the ability to close one's eyes?

The orbicularis oculi is the muscle primarily responsible for closing the eyes. This muscle encircles the eye socket and is involved in the blinking process and in fully closing the eyelids. When the orbicularis oculi contracts, it pulls the eyelids together, which helps protect the eye from foreign objects, bright lights, and assists in the distribution of tears across the ocular surface.

The other muscles mentioned play different roles. The masseter is involved in the movement of the jaw and is crucial for chewing. The frontalis helps in raising the eyebrows and expressing surprise or concern. The zygomaticus is responsible for smiling and pulling the corners of the mouth upward. Each of these muscles has distinct functions that do not involve controlling the eyelids directly, affirming the orbicularis oculi as the correct choice for eye closure.