Assertion: Chronic stress can weaken the immune system.

Reasoning: Prolonged exposure to stress hormones can suppress immune function, making individuals more susceptible to illnesses.

Both Assertion and Reasoning are true, and the Reasoning is the correct explanation of the Assertion.

The correct answer is (a) Both Assertion and Reasoning are true, and the Reasoning is the correct explanation of the Assertion.

Chronic stress has been linked to a weakened immune system. Prolonged exposure to stress hormones can suppress immune function, making individuals more susceptible to infections, viruses, and other illnesses. Additionally, chronic stress can also lead to inflammation, which further compromises the immune system's ability to function optimally.