Which of the following biological theories of aging states that people age because their cells' normal metabolism produces unstable oxygen molecules? A. Cellular clock theoryB. Free-radical theoryC. Telomerase-injection theoryD. Hormonal stress theory

B. Free-radical theory

Explanation:

The free radical theory statutes that ageing is the result of the accumulation of the damage to cells and tissues caused by reactive oxygen species as a result of aerobic metabolism.

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