PATHOLOGY

Detailed explanation-1: -Answer and Explanation: Fever is not the first line of defense; it is considered the second line of defense. Suppose the first line of defense couldn’t protect the body, and the pathogen still enters the body. In that case, the second line of defense protects the body, including fever, inflammation, and phagocytosis.

Detailed explanation-2: -The innate immune system is the body’s first line of defense against germs entering the body. It responds in the same way to all germs and foreign substances, which is why it is sometimes referred to as the “nonspecific” immune system.

Detailed explanation-3: -So, the correct answer is ‘Killer T-cells’.