_______ often happens, people with good eyesight fail to see _______is right in front of them, for they have too much to observe.

A. It / that         B. As/ which        C. It/what        D. As/ what

It often happens that people with good eyesight fail to see      is right in front of them.

It often happens that people with good eyesight fail to see______is right in front of them.

1. A.
   which
2. B.
   that
3. C.
   what
4. D.
   as

It often happens that people with good eyesight fail to see       is right in front of them.

A. which                      B. that                   C. what                 D. as