The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
Oxidative phosphorylation is the metabolic pathway in which the mitochondria in cells use their structure, enzymes, and energy released by the oxidation of nutrients to reform ATP. The enzyme required for ATP synthesis is called ATP synthetase. Thus, both the assertion and reason are correct. But, reason is not the correct explanation for the assertion.