Step 1: Concept
The Simple Present tense is used to state universal truths, scientific facts, or habitual actions.
Step 2: Meaning
The movement of the Earth around the Sun is a permanent, scientific fact.
Step 3: Analysis
For singular subjects ("The earth") in the Simple Present tense, the verb adds an 's' or 'es'.
Step 4: Conclusion
"Revolves" is the correct scientific and grammatical form.
Final Answer: (B)