Will you join us in the game?

Will you join us in the game?
.—Will you join us in the game?
—Thank you,
A.but why not?B.but I’d rather not.
C.and I won’t D.and I’ll join.
why choose b,thank you.
您的意思是thank you 相当于no?
那为什么A和D在句意逻辑上就排除了？没有哪里有暗示阿