Answer:
The correct answer would be the enzyme and substrate.
Explanation:
The lock and key theory is specific of an enzyme and substrate. In the lock and key mechanism the enzymes that catalyze chemical reactions begins with the binding of substrate to the active site of the enzyme called enzyme-substrate complex. It is basically like the key and the lock where the lock is the enzyme and key is a substrate which fits in the groove called active site.
The enzyme-substrate complex result in products and enzyme after the chemical reaction.
Thus, the correct option would be the enzyme and substrate.
