Correct Answer: Virus

Solution : The correct option is Virus

A kind of influenza virus is the source of the highly contagious respiratory disease known as "swine flu," which primarily affects pigs. This virus, however, can also infect humans. Swine flu symptoms are similar to that of the seasonal flu and can include fever, cough, sore throat, body pains, exhaustion, and, in some cases, diarrhoea and vomiting. In extreme cases, it can cause pneumonia and respiratory failure. Swine flu, like ordinary flu, can spread from person to person via respiratory droplets.