Answer:

All of the above are the right answer (a, b, and c).

If you are asking which one is the most right, then I would say that hydrogen peroxide is the most right answer (c).

Explanation:

The scratch papers and bottle are both tools to be used in making your volcano model, whereas hydrogen peroxide is the actual chemical that will cause the reaction.

Without the scratch papers and bottle, you still theoretically have the chemical necessary to create the reaction. Without the hydrogen peroxide, however, you have nothing.