The question that puzzled them is ____ they can get rid of the air pollution in the area.

A. how is it that      B. that how                      C. that it is how              D. how it is that

The question that puzzled them is ____ they can get rid of the air pollution in the area.

A. how is it that    B. that is how     C. what is that      D. how it is that

The question that puzzled them is ____ they can get rid of the air pollution in the area.

A. how is it that    B. that how     C. what is it      D. how it is that

The question that puzzled them is ______ they can get rid of the air pollution in the area.

1. A.
   how is it that
2. B.
   that how
3. C.
   what is it
4. D.
   how it is that