The correct answer is: A. luminous heavenly bodies revolving around a star.
A planet is a large, round object that orbits a star. Planets are made of rock or gas, and they do not produce their own light. They reflect the light of the star they orbit. Planets are much smaller than stars, and they do not have enough mass to start nuclear fusion in their cores.
Option B is incorrect because planets are not non-luminous. They reflect the light of the star they orbit.
Option C is incorrect because planets do not twinkle. The twinkling of stars is caused by the movement of air in Earth’s atmosphere. Planets are much closer to Earth than stars, so they appear larger and do not twinkle.
Option D is incorrect because planets are luminous. They reflect the light of the star they orbit.