Final answer:
The body's reaction to exposure to or invasion by antigens is best described as the immune response. This response involves the activation of the adaptive immune system, including T and B cells, to attack and eliminate the invading antigens.
Step-by-step explanation:
The body's reaction to exposure to or invasion by antigens is best described as the immune response. This response is a complex process that involves the activation of the adaptive immune system to eliminate the invading antigens.
When the innate immune response is insufficient to control an infection, the adaptive immune response is mobilized and involves the activation of T and B cells, which attack the pathogen by killing it directly or by secreting antibodies to enhance phagocytosis and disrupt the infection. The adaptive immune response also involves the development of memory to provide long-term protection against reinfection.