This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Oncherciasis elimination, operational definition ? 
Select and explain. 
A. O.volvulus transmission has reduced below a paicular point, B. Intervention has stoped, C. No recrudescence, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Ans. is 'd' i.e., All of the above Oncherciasis elimination The reduction of infection and transmission to the extent that interventions can be stopped, but post-intervention surveillance is still necessary. Operational definition includes ? Intervention have reduced O.volvulus infection and transmission below the point where the parasite population is beilved to be irreversibly moving to its demise/extinction in a defined geographical area. Intervention have been stopped. Post-interventional surveillance for an appropriate period has demonstrated no recrudescence of transmission to a level suggesting recovery of O.volvulus population. Additional surveillance is still necessary for timely detection of recurrent infection, if a risk of reintroduction of infection from other area remains.