Answer: Option (1) is the correct answer.
Step-by-step explanation:
A catalyst is defined as the substance that helps in decreasing the activation energy of a chemical reaction so that more number of reactant molecules can participate in the reaction.
During this process the catalyst doesn't get consumed in the chemical reaction.
As a result, a catalyst also helps in increasing the rate of a chemical reaction.
Thus, we can conclude that a substance that changes the rate of the reaction and is not consumed in the reaction is known as a catalyst.