Rennin used in cheese industry is an
A. Antibiotic
B. Alkaloid
C. Enzyme
D. Inhibitor

Hint: Rennin is also called chymosin. It is synthesized by chief cells in the stomach of some animals, soit is found only in the fourth stomach of cud –chewing animals, such as cows. It helps in coagulation of milk in the stomach of young animals or it helps to convert liquid milk to a semisolid cottage cheese.

Complete answer :-
To answer this question you must know about the role of rennin.
Rennin is a proteolytic enzyme also called chymosin related to pepsin that is synthesized by chief cells in the stomachs of some animals. Rennin mainly converts liquid milk to a semisolid like cottage cheese or we can say it helps in the coagulation and curdling of milk, allowing it to be retained in the stomach for a longer period of time. This process is very important especially in young animals because if milk were not coagulated, it would rapidly flow through the stomach and miss the opportunity for initial digestion of its protein.
Considering other example:
Antibiotics are medicines that fight with the infections in people and animals,also known as antibacterial.
Alkaloids are a huge group of naturally occurring organic compounds which contain nitrogen atoms or atoms.
Inhibitor is a substance which slows down or prevents a particular chemical reaction or other process.

Thus the correct answer of the given question is option (C) Enzyme.

Note:-
Due to the coagulating action of milk, rennin enzyme is commonly used in the food industries. It is widely used in the cheese industry. However, for industrial cheese production, a large amount of rennin is required. So for three days, genetic engineering methods are used for obtaining a large amount of rennin enzymes needed for the food industry.