Which of the following is a common viral infection of the respiratory tract?

Influenza is a well-known viral infection that primarily affects the respiratory tract. It's caused by the influenza virus, which can lead to symptoms such as fever, cough, sore throat, body aches, and fatigue. The virus spreads easily through respiratory droplets when an infected person coughs, sneezes, or talks, making it a common illness during certain seasons, particularly the winter months.

The other options, while they are diseases caused by viruses or other pathogens, do not primarily affect the respiratory system. Chickenpox, for instance, is a viral infection caused by the varicella-zoster virus, prominently affecting the skin and causing a characteristic itchy rash. Measles, caused by the measles virus, can affect the respiratory tract and lead to complications, but its primary symptoms include high fever and a widespread rash that follows. Lyme disease, on the other hand, is caused by the bacterium Borrelia burgdorferi and is transmitted through tick bites, leading to different clinical manifestations primarily affecting the skin, joints, and nervous system, rather than the respiratory system. Thus, influenza stands out as the common viral infection notably affecting the respiratory tract.