Answer:
The Answer is D. Number 3.
Explanation:
To answer this question you'll need to know what a Dependent Variable is, by textbook definition, a Dependent Variable is a Variable (Variable such as Y, X) that is Dependent on the equation. In this case, D is dependent on 25 * H because 25 * H is what D equals. (A lot of times the Dependent Variable is what is on the = side of the equation.)
Hope this makes sense, best of luck <3