can you please provide an explanation to this question?

If I verbally tell my 16 year-old son that I will give him $10,000, if he doesn't drink alcohol until he is 20 years-old. Decide on the best answer. a. This is not a legally enforceable contract, because it is $10,000. b. This is not a legally enforceable contract, because it is for more than a year in time. c. This is not a legally enforceable contract, because consideration is missing. d. band c e. All of these