We are very sad and angry to hear that the bad milk powder--

We are very sad and angry to hear that the bad milk powder____ the deaths of over 30 babies.We are very sad and angry to hear that the bad milk powder(劣质奶粉)____ the deaths of over 30 babies.A.made B.did C.brought D.caused为什么不能选A呢?请说一下原因