The correct option is C Air borne diseases
If you live in an overcrowded and poorly ventilated house, it is possible that you may suffer from some air borne diseases. The chances of spreading the air borne diseases are more in the crowded and poorly ventilated area. This is because, in such areas, the person infected with some disease easily spreads the infectious droplets through breathing and sneezing. These infected droplets are inhaled by the healthy person who can become infected. In addition, if the house is not properly ventilated, the infectious droplets keep on circulating in the closed area and hence more and more people can become infected with the disease.