What does "antiviral resistance" refer to?

Antiviral resistance specifically refers to the ability of a virus to withstand the effects of antiviral medications that are designed to inhibit its replication, thereby rendering those medications less effective or ineffective. This phenomenon occurs when viruses undergo mutations or evolve in ways that allow them to escape the mechanisms of action of the antiviral agents. By successfully adapting to the presence of an antiviral drug, the virus can continue to proliferate despite treatment efforts, making it a significant challenge in managing viral infections.

The other concepts mentioned in the options do not accurately define antiviral resistance. For instance, while rapid replication of a virus may contribute to the development of resistance, it is not the definition itself. Similarly, the method of antiviral administration and the ability of an antiviral to mutate do not pertain to the concept of a virus resisting the effects of treatment. Hence, option A captures the essence of antiviral resistance effectively.