Identify the type of error in the sentence. If the sentence contains no error, select

c. A catalyst is where a chemical begins the reaction but does not participate in it

In the sentence given above, the correct form should be:

c. A catalyst is where a chemical reaction begins but does not participate in it.

You can omit the article "the" and the word "reaction" which is modified by the adjective "chemical" must be put after the modifier to provide a concise sentence.