Chemists can use moles to calculate: a. how much of the products are needed and how much reactant will be made. b. how much product will be made, but not how much of the reactants are needed. c. how much of the reactants are needed and how much product will be made. d. how much of the reactants are needed, but not how much product will be made.

c.- How much of the reactants are needed and how much product will made.

Explanation:

The moles is the matter unit used in chemistry to simplify  some calculations, instead of using grams. Also the moles are very useful because the chemical reaction can be balanced.

When a Chemical reaction is balanced, then it can be easily to calculate how many moles are necessary to add in a process to obtain a quantity of grams of a product.