In human beings influenza is caused by:

a) bacteria

b) protist

c) virus

d) fungi

Viruses travelling through the air are the cause of influenza in human beings. They travel in shape of droplets when someone with the infection coughs, sneezes or talks. Human beings can inhale the virus directly or, they may pick up the germs from objects. Influenza viruses keep on changing themselves, with new strains appearing regularly. Human body naturally make antibodies to fight against specific strains of virus.