What is immunity?

Immunity refers to the body's ability to resist or defend against infection and disease. This protection can be inherent, as seen with natural immunity, or can result from exposure to an infectious agent that leads to the production of antibodies, a hallmark of acquired immunity. Essentially, immunity enables a person to fend off pathogens or their effects, which is the core of why "protection against a disease or condition" is the correct understanding of the term.

The other options focus on different aspects of health and hygiene. The practice of sterilization pertains to eliminating all forms of bacteria and pathogens, which is not the same as immunity. A state of paralysis is a dysfunction that affects movement and does not relate to the body’s defense mechanisms. Lastly, the process of microbe removal is linked to cleaning and infection control, but again, it does not encompass the protective biological response that immunity provides. Therefore, the definition of immunity as protection aligns best with understanding how our bodies maintain health against harmful agents.