I received his mother’s telephone call at eleven.＿＿that he was badly hurt in an accident yesterday.

A.Then did I know B.Only then I knew  C.Only then did I know D.Only then knew I

I received his mother’s telephone call at eleven.＿＿that he was badly hurt in an accident yesterday.

1. A.
   Then did I know
2. B.
   Only then I knew
3. C.
   Only then did I know
4. D.
   Only then knew I