Chemical equilibrium results if
1. all reactants are used up
2. some products are removed
3. more reactants are added
4. forward reaction rate equals reverse reaction rate

Option D,  forward reaction rate equals reverse reaction rate

Explanation:

When there is no observable change in any chemical reaction, then it is said that chemical equilibrium has reached.

At this stage the concentration of both the reactants and products is constant and hence forwards rate of reaction becomes equal to the backward reaction rate. There exists no  observable change in the properties of the system and its components

hence, option D is correct

sorry, but you do not have posted the diagram.

"d.) carbon dioxide and hydrogen sulfide"