Answer: Antioxidant
Step-by-step explanation:
Antioxidants are the compounds that prevent the oxidation. The oxidation is a chemical process it can produce free radicals. This leads to the chain reaction which can damage the cells of the organisms.
The process of oxidation in human beings can damage the cell membranes and other structures in the body like DNA, proteins and lipids.
Antioxidants like ascorbic acid and thiols can terminate the chain reactions in the body and will prevent oxidation.
On the basis of the above explanation, antioxidant is the correct option which has been discovered by the scientists.