Choice A rationale:

Administering antiviral medications is not a standard treatment for infectious mononucleosis. The infection is usually caused by the Epstein-Barr virus, and antiviral medications are not effective against it.

Choice B rationale:

Encouraging adequate fluid intake is essential for a patient with infectious mononucleosis. It helps prevent dehydration, which is especially important if the patient has a fever or is experiencing other symptoms that may lead to fluid loss.

Choice C rationale:

Advising the patient to rest and avoid strenuous activities is crucial. Rest is essential to support the body's immune response and to prevent complications from the infection.

Choice D rationale:

Providing comfort measures for a sore throat, such as warm saline gargles, is appropriate. Sore throat is a common symptom of infectious mononucleosis, and these measures can help soothe the discomfort.

Choice E rationale:

Instructing the patient to eat a high-protein diet to support immune function is not specifically indicated for infectious mononucleosis. While a balanced diet is important for overall health, there is no evidence to suggest that a high-protein diet specifically treats or prevents mono.