When he came to the door, my father ___ him at once although he was now a very old man.

1. A.
   knew
2. B.
   looked at
3. C.
   recognized
4. D.
   found

When he came to the door, my father ___ him at once although he was now a very old man.

A. knew　  B. looked at　  C. recognized　   D. found

When he came to the door, my father ___ him at once although he was now a very old man.