An enzyme increases the speed of a reaction:

Explanation

Enzymes serve as biological catalysts that increase the rate of chemical reactions by lowering the activation energy required for the reaction to proceed. Activation energy is the minimum amount of energy needed to initiate a reaction. By providing an alternative reaction pathway with a lower activation energy, enzymes allow reactions to occur more rapidly.Option A is incorrect because enzymes do not add to the activation energy requirements; they reduce them. Option C is incorrect because enzymes do not alter the equilibrium position of the reaction; they only accelerate the rate at which equilibrium is reached. Option D is incorrect because while enzymes affect the rate of reaction, they do not directly change the concentration of products.