In the natural history of disease, all are true about the period of pathogenesis, EXCEPT:

Screening is defined as the search for unrecognized disease or defect by means of rapidly applied tests, examinations or other procedures, in an apparently healthy individual. By screening we can identify the disease early and can stop the duration of pathogenesis of disease. So indirectly it decreases time of pathogenesis. Natural history of disease stas only after the entry of the pathogen in to the body. There should be sub-clinical cases during the pathogenesis. Teiary prevention does not affect the time of pathogenesis. So most probable answer is C. Ref: Textbook of Preventive and Community Dentistry By Hiremath, 2006, Page 30