What does vaccination involve?

Vaccination involves the introduction of a harmless microorganism, often in the form of a weakened or inactivated pathogen, into an animal's body. This process stimulates the immune system to recognize the microorganism as a threat, creating a memory of it. As a result, the immune system develops specific antibodies against the microorganism, leading to acquired immunity. When the animal is later exposed to the actual pathogen, its immune system can respond more quickly and effectively, reducing the severity of the disease or preventing it altogether.

The other options describe practices related to veterinary care but do not pertain to vaccination. For instance, the removal of harmful pests pertains to parasitology and pest control, while monitoring animal health involves regular check-ups and assessments of health statuses. Providing nutrition to sick animals focuses on dietary support rather than the immunological protection that vaccination provides.