$\begin{array}{1 1} \text{(a) A catalyst is a substance that speeds up the rate of a chemical reaction and also reduced during the course of the reaction.} \\ \text{(b) A catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.} \\ \text{(c) A catalyst is a substance that reduces the rate of a chemical reaction but is not consumed during the course of the reaction.} \\ \text{(d) A catalyst is a substance that speeds up the rate of a chemical reaction and it is consumed during the course of the reaction.} \end{array} $
