Why can the Moon sometimes be seen in the daytime sky?

Answer: Sunlight lights the Moon, so its bright surface can show against the daytime sky.

Sunlight lights the Moon, so its bright surface can show against the daytime sky. ✓ — Correct! The Moon does not make its own light; sunlight falls on it and makes it bright enough to see. During daytime it is often above the horizon, and when sky conditions cooperate its lit surface can stand out against the blue background.

The Moon can appear in daytime only when it is full and completely lit by the Sun. — The Moon does not need to be full to be seen in daylight. It can be visible in many phases when it is above the horizon and bright enough to stand out against the sky.

Clouds in the daytime sky reflect extra sunlight onto the Moon and brighten it. — Clouds do reflect sunlight, so this answer gets one part half right. But the light they send toward the Moon is too little to brighten it noticeably, and clouds more often hide the Moon in the daytime.