Which of the following is not a criteria for over crowding -

Overcrowding refers to situation in which people are living within a single dwelling than there is space for,so that movemwnt is restricted,privacy secluded,hygiene impossible,rest and sleep difficult. Criteria for overcrowding are: 1)person per room: 1 room -2 persons,2 room-3 persons.. 2) floor space: 110 sq.ft.-2 persons 3)sex separation: overcrowding is considered to exist if 2 persons over 9 years, not husband and wife, of opposite sex are obliged to sleep in same room. So number of windows per room is not a criteria for overcrowding. Parks textbook of preventive and social medicine.K Park. Edition 23.Pg no: 752