Helen Tells Her Nephew,Bernard,that She Will Pay Him $100 If

Helen tells her nephew,Bernard,that she will pay him $100 if he will stop smoking for six months.Helen was hopeful that if Bernard stopped smoking for six months,he would stop altogether.Bernard stops smoking for six months and then resumes his smoking.Helen will not pay him.She says that the type of promise she made cannot constitute a binding contract and that,furthermore,it was at least implied that he would stop smoking for good.
Can Bernard legally collect $100 from Helen?

A) No,because under the law his stopping smoking was not adequate consideration.
B) No,because it was implied that he would stop smoking for good,and he only quit for six months.
C) Yes,because his stopping smoking for six months,as agreed,was adequate consideration for the contract.
D) Yes,because stopping smoking was good for his health even if he only did it for six months.