Which of the following diseases is caused by a virus?

The correct answer includes both yellow fever and hepatitis B as diseases caused by viruses. Yellow fever is an acute viral disease transmitted by infected mosquitoes, leading to symptoms such as fever, chills, loss of appetite, and muscle pain. It is primarily found in tropical regions and can lead to severe complications or death if not managed correctly.

Hepatitis B is also a viral disease, specifically caused by the hepatitis B virus (HBV), which primarily affects the liver. It can lead to both acute and chronic infections, and it spreads through contact with infectious body fluids, most commonly through sexual contact or sharing needles.

On the other hand, salmonella is a type of bacteria that causes foodborne illnesses and is not caused by a virus. Thus, the selection that includes both yellow fever and hepatitis B properly identifies two diseases that are viral in nature, affirming the choice that includes both A and C.