It was very difficult to rescue the drowning boy in the sea.

It was very difficult to rescue the drowning boy in the sea.One moment the rescue
workers ____him
but the next moment they _____.
[ ]
A.caught sight of; lost
B.caught the sight of; lost his sight
C.caught sight of; lost sight of him
D.caught the sight of; lost their sight of him
为什么答案选A
C为什么不行