The correct option is A revolves
The given statement states a universal truth, which will not change anytime soon. Hence, it's in simple present tense. (The simple present states a habit, a fact or a general truth.)
The underlined verb "is revolving" is in present continuous. Hence it must be changed to its appropriate tense form and D is incorrect.
Option A: 'Revolves' is a verb form in the simple present tense. Hence A is correct.
Option B: 'Has revolved' is in present perfect. It indicates that an action has been completed recently. It does not express a universal truth. Hence B is incorrect.
Option C: 'Revolved' is in the simple past tense. It describes an action completed in the past. Hence C is also incorrect.