The disease that is caused by a virus is

Diseases are classified by the type of pathogen (disease-causing agent) responsible for them: bacteria cause bacterial infections, viruses cause viral infections, and protozoan parasites cause parasitic infections. Identifying the pathogen type is the key skill being tested here.

Among the four diseases listed, only one is caused by a virus. Rhinoviruses, along with other viruses such as certain coronaviruses, are responsible for the common cold, which makes it the viral disease in this set.

• Typhoid is caused by the bacterium Salmonella typhi — a bacterial infection, not viral.

• Cholera is caused by the bacterium Vibrio cholerae — also bacterial, not viral.

• Malaria is caused by protozoan parasites of the genus Plasmodium, transmitted through the bite of an infected Anopheles mosquito — a parasitic disease, not viral.

• Common cold is caused by viruses (mainly rhinoviruses) — the only viral disease among the four.

So, the disease caused by a virus among the given options is the common cold.