A. She said that the Earth revolved around the Sun.
B. She said that the Earth had revolved around the Sun.
C. She said that the Earth revolves around the Sun.
D. She said that the Earth is revolving around the Sun.
Correct answer is: C. She said that the Earth revolves around the Sun.
The statement is a universal fact, so the present tense 'revolves' is retained in indirect speech.