Answer: Option (A) is the correct answer.
Step-by-step explanation:
Activation energy is the minimum amount of energy required to carry out a chemical reaction.
So, when reactant molecules does not have the minimum amount of energy then they are not able to participate in a chemical reaction. Hence, the reaction does not take place.
Therefore, a catalyst acts as an initiator in this situation to carry out the reaction.
Thus, we can conclude that the importance of the activation energy acting as a barrier for reactants as it prevents most reactions from occurring spontaneously.