A:that; that; possible
B:which; that; impossible
C:which; what; possible
D:what; which; possible
胡佛在其美国总统竞选辞中称:他会使家家锅里有一只鸡,家家有一辆车。但他的诺言在1929年被无情地粉碎了。“粉碎”其诺言的是( )