The water there was blue and clean.

[sitifan]

The water ____ was blue and clean.
(A) there
(B) in there
(C) on there
(D) at there

There is no context to the above question. The answer is option A. How about the acceptability of the other options?

 

[tedmc]

I think B and C are also acceptable in certain contexts but A is more general.

 

[Rover_KE]

There is no context to the above question.

There has to be a context. Where did you find this question?

 

[sitifan]

There has to be a context. Where did you find this question?

It's a test question designed by a Taiwanese teacher of English. There is no context.