Energy of activation a. is the energy required for molecules to react with each other. b. requires the use of enzymes. allows for feedback inhibition. c. acts on the products of metabolic reactions. d. is a measure of the amount of solar radiation striking a leaf surface.

Option A) is the energy required for molecules to react with each other

Explanation:

Since each molecule partaking in a reaction possess intramolecular bonds (within their atoms) holding them together; for reaction to occur, an equal or higher energy is required to break through the intramolecular bonds and propel reacting molecules to combine and form products.

This required energy is called ACTIVATION ENERGY, and it is often lowered by catalysts

Option A.

Explanation:

Energy of activation is the energy required to start chemical reaction from the reactants state to the energy level of transition state.

It is the amount of energy that is available for reaction to take place.

For any reaction to take place, there must be activation energy which will make the reaction to take place and get to transition state.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.