The best way to make them work hard is to promise them reward

Choose A, B, C or D to indicate the sentence that is similar in meaning to the one given.

The best way to make them work hard is to promise them reward.

• A. Promise them a reward and they will work hard.
• B. If you promise to reward, they will word hard.
• C. Reward them and make them work hard.
• D. If they work hard, you should promise to reward them.