Which One of the Following Statements Is Believed to Be

Multiple Choice

Which one of the following statements is believed to be true of comets?

A) They have highly elliptical orbits around the Sun.
B) They are composed mostly of dense rock particles.
C) They may gain slightly in mass with each orbit around the Sun.
D) Their bright,glowing appearance in the night sky is due to frictional heating in Earth's atmosphere.