‘I'll buy you a new bicycle if you stop eating junk food,' said Lam's mother

A. Lam's mother promised to buy him a new bicycle if he stopped eating junk food.

B. Lam's mother promises to buy him a new bicycle if he stops eating junk food.

C. Lam's mother will promise to buy him a new bicycle if he stops eating junk food.

D. Lam's mother had promised to buy him a new bicycle if he stopped eating junk food.