What type of viral infection is highly contagious and can mutate?

Influenza is the correct choice because it is a viral infection characterized by its high contagion and the ability to mutate rapidly. Influenza viruses are known for their antigenic shifts and drifts, which occur when the virus undergoes genetic changes, leading to new strains. This mutation allows the virus to evade the immune system, contributing to annual outbreaks and the need for updated vaccines each flu season.

In contrast, leukemia is a type of cancer that affects the blood and bone marrow and is not caused by a viral infection. Malaria is a parasitic disease caused by Plasmodium species and is transmitted through mosquito bites, not a virus. Measles is indeed highly contagious, but it does not mutate as extensively or frequently as the influenza virus. Understanding the distinguishing characteristics of these conditions is crucial in identifying viral infections specifically associated with high contagion and mutation rates.