The correct construction here is ”can earn,” as the modal verb ”can” is followed by the base form of the verb ”earn.” The other options are grammatically incorrect
List I | List II |
(A)Fits and starts | (1) At appropriate time |
(B)In less than no time | (II) At intervals |
(C) Once in a blue moon | (III) In a moment |
(D) On the dot | (IV) Rarely |