Final answer:
Prophylactic is best explained as preventing the occurrence of a condition, such as vaccines preventing the occurrence of specific infectious diseases.
Step-by-step explanation:
Prophylactic is best explained as preventing the occurrence of a condition. This can be seen in the example of vaccines, which prevent the occurrence of specific infectious diseases. Vaccination is a form of artificial immunity that stimulates the immune system to produce memory cells and mount a strong response upon exposure to the disease.