The right answer is the catalyst.
In chemistry, a catalyst is a substance that increases the rate of a chemical reaction; it participates in the reaction but it is neither part of the products nor reagents and therefore does not appear in the equation-balance of this reaction.
The catalyst accelerates, sometimes in considerable proportions, the chemical reaction, but it is not consumed: either it does not participate in the reaction but its presence facilitates the breakage of the bonds, or it participates but is regenerated at the end.
Catalysts are widely used in industry and laboratory.
In nature and in biochemistry, some proteins have catalytic activity. They are enzymes.