Which of the Following Is the Best Definition of a Catalyst

Which of the following is the best definition of a catalyst?

A) A catalyst is a material which speeds up the rate of a chemical reaction.
B) A catalyst is a material which speeds up the rate of a chemical reaction without participating in the reaction.
C) A catalyst is a material which speeds up the rate of a chemical reaction without being consumed during the reaction.
D) All of the above are equally good definitions.