Observe the given graph showing the concept of activation energy...

The given graph illustrates the concept of activation energy for a chemical reaction, comparing the energy profiles of an uncatalyzed and a catalyzed reaction.

Label A points to the peak of the energy profile, which represents the transition state where the substrate is in the process of being converted into the product.

Label B represents the activation energy required for the reaction to proceed without an enzyme. It is the energy difference between the substrate and the transition state of the uncatalyzed reaction.

Label C represents the activation energy required for the reaction to proceed with an enzyme. Enzymes act as catalysts to lower the activation energy, so this energy barrier is smaller than B.

Therefore, A is the transition state, B is the activation energy without enzyme, and C is the activation energy with enzyme.

Answer: A - Transition state; B - Activation energy without enzyme; C - Activation energy with enzyme