Answer:
Option (D) By observing illuminated mountain peaks in the dark portion of the moon.
Step-by-step explanation:
Unlike the traditions at the time of Aristotle which considered that the celestial bodies are spherical and perfectly smooth bodies.
But based on Galileo's observations, the zone that was illuminated in the dark region of the moon near the line that separates the illuminated and the shadowy parts, known as terminator was noticed.
On the breaking of the dawn, as the sunlight hit the top of the lunar mountains it lightens up while the valleys are still dark.