What is the tense of the underlined verb in the sentence?

the moon revolves around the earth.

a.
simple present

b.
simple future

c.
simple past

Option a is the write answer

  i think you forgot to put the options but if your reffering to this question then your answer will be "b"  a. add "to" to the base form to create an adjective.b. when the subject of a sentence is singular, add "–s" to the base form.c. add "–ed" to irregular base forms to form the past participle.d. do not use a base form with plural subjects