PATHOLOGY

Detailed explanation-1: -The third line defense aims at eliminating specific pathogens that have been encountered by the immune system previously (adaptive or acquired immune response). Instead of being restricted to the site of infection, the adaptive immune response occurs throughout the body.

Detailed explanation-2: -The first line of defence is made up of barriers to prevent infection. The second line of defence is made up of responses to infection that apply generally to all pathogens. The third line of defence provides immunity against specific pathogens.