When exposure to a disease organism triggers the immune system to produce antibodies to that disease, it is called:

The correct answer is active immunity because this term specifically refers to the process where an individual's immune system responds to an infection or vaccine by producing antibodies. When exposed to a disease organism, the immune system recognizes the antigens on the pathogen and mounts a response by generating specific antibodies against it. This response helps the body to fight off the disease and develop a memory of the pathogen, which can provide long-lasting protection in case of future exposures.

Active immunity can be achieved through natural infection or through vaccinations that simulate infection without causing the disease itself, leading the immune system to prepare itself for future encounters with the pathogen. This distinguishes it from other types of immunity, such as passive immunity, which involves the direct transfer of antibodies from one person to another (for example, from mother to baby through breastmilk), and does not require the immune system to actively produce antibodies.

Natural immunity refers to the immunity that occurs due to actual exposure to a pathogen during life, while acquired immunity encompasses both active and passive immunity, as it describes how immunity is gained during a person's life either through exposure to diseases or through vaccinations, rather than being innate.