
Extract the answer to the question from the following context.
Question: In a body, the ability to distinguish between molecules that are from the organism's own body and that of a foreign substance allows for the organism to stay healthy by initiating what type of action?
Context: Both innate and adaptive immunity depend on the ability of the immune system to distinguish between self and non-self molecules. In immunology, self molecules are those components of an organism's body that can be distinguished from foreign substances by the immune system. Conversely, non-self molecules are those recognized as foreign molecules. One class of non-self molecules are called antigens (short for antibody generators) and are defined as substances that bind to specific immune receptors and elicit an immune response.

an immune response
