Why not "Где она утку видит?" ?
Possible, but it's rather harsh.
Suggested answer is "утка" when corect it is "утку".
Why not утка?
When you use a transitive verb in Russian, the direct object of the verb must be put into the accusative case. Hence: утка -> утку.
Где видит она утку?
also possible :)
why она and not ей ? and why утку but not утка ??
Because it's not in dative case. "She" is the subject, and had to be in nominative case. And "duck", being preceded by transitive verb, must be in accusative
The hint said утка. Should it be fixed?
Why not "Где она увидела утку?"?
Because your sentence is in the past and the current example is not.
Why not "Она видит утку где?"?
Why is "Где видит она утку?" wrong?
1. She is in Germany and she sees a duck.
2. She sees a duck that is in the pond.