What are the two main types of immunity?

The correct answer highlights the distinction between active and passive immunity, which are two key categories of acquired immunity. Active immunity occurs when an individual's immune system is exposed to a pathogen and generates a response, creating memory cells that provide long-term protection. This can happen naturally through infection or artificially via vaccination. On the other hand, passive immunity is acquired when antibodies are transferred from one individual to another, providing immediate but temporary protection. This method is often seen in newborns receiving antibodies from their mothers or through antibody therapies.

Natural and acquired immunity describes the sources of immune responses rather than categorizing them based on activity. While cell-mediated and humoral immunity are specialized responses within the immune system, they do not encompass the broader classification of how an immune response is developed. Similarly, specific and non-specific immunity refer to the targeting mechanisms of the immune system rather than the categorization of immunity based on the source of the immune response. Understanding the difference between active and passive immunity is crucial in immunology, particularly regarding vaccine development and treatment strategies.