Enzymes affect the reactions in living cells by changing what?

Speed of Biochemical Reaction (Lowering the Activation energy)

Explanation:

Enzymes are catalyst that speeds up the rate of biochemical reaction in living organism. They are protein in nature and they are involved in every process that take place in living organisms such as breaking down of food to building up of protein. In living organism, enzymes speed up the rate of chemical reaction by lowering the activation energy thereby bringing the reactants close to each other and weaken there chemical bonds which will enable the reactions to be faster.

coal is not sustainable because it will one day run out.

it is either c or d and i know for sure it is not a or b