Which of the following is an example of a respiratory pathogen?

The Influenza virus is classified as a respiratory pathogen because it primarily infects the respiratory system, leading to illnesses such as the flu. It spreads through respiratory droplets when an infected person coughs or sneezes, and it can cause symptoms like cough, sore throat, and fever. Understanding the behavior and transmission of respiratory pathogens is crucial in infection control measures, especially in settings where individuals are in close contact, such as healthcare facilities or schools.

In contrast, the other options are associated with different types of infections. Streptococcus bacteria can cause respiratory infections, but they also have a broader range of effects, including skin infections and sore throats. Escherichia coli is primarily known for causing gastrointestinal infections, not respiratory ones. Hepatitis B virus specifically targets the liver and is not a respiratory pathogen at all. Therefore, the distinguishing characteristic of the Influenza virus as a pathogen primarily affecting the respiratory tract solidifies its classification in this context.