Answer:
The correct option is B. It is unchanged and can be used for the same chemical reaction.
Step-by-step explanation:
Enzymes can be described as proteins which act as biological catalysts. Enzymes can speed up a reaction. During this process, the enzyme itself doesn't get consumed and hence, it can be reused. Enzymes are specific for a particular type of substrate and hence, they can catalyze only those reactions for which they are specific. Hence, option B is correct.
Other options like option A is not correct because the mass of an enzyme will not change after a reaction.