Question

enzymes speed chemical reactions by
lowering the amount of reactants that are needed.
maintaining temperature.
lowering the energy required to start a chemical reaction.
raising the temperature of the surroundings.
supplying energy to the reaction process.

Explanation:

Enzymes are biological catalysts. The key role of a catalyst (including enzymes) is to lower the activation energy (the energy required to start a chemical reaction) of a reaction. They do not change the amount of reactants needed, do not primarily function to maintain or raise temperature, and do not supply energy to the reaction (they lower the energy needed instead). So the correct option is the one about lowering the energy required to start a chemical reaction.

Answer:

C. lowering the energy required to start a chemical reaction. (Note: Assuming the third option is labeled C; if the original options had different labels, adjust the label accordingly based on the original numbering, e.g., if it's the third option in the list as presented, with the first being A, second B, third C, etc.)