The installation and usage of sanitary latrines by the general public constitutes which level of prevention?

Primary prevention is concerned with preventing the onset of disease; it aims to reduce the incidence of disease. It involves interventions that are applied before there is any evidence of disease or injury. Examples include protection against the effects of a disease agent, as with vaccination, garbage collection, refrigeration of food, etc. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 48