This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Air, Light, Sound, Housing, Radiation, Waste Disposal, Subject name: Social & Preventive Medicine
Which of the following is not a method of controlled tipping? 
Select and explain. 
A. Trench method, B. Ramp method, C. Area method, D. Slope method
D: Slope method
Answer: D: Slope method 
Explanation: Controlled tipping or sanitary landfill Most satisfactory method of refuse disposal where suitable land is available. "Modified sanitary landfill" has been applied to those operations where compaction and covering are accomplished once or twice a week. 3 methods Trench method: Where level ground is available. Ramp method : Terrain is moderately sloping. Some excavation is done to secure the covering material. Area method: This method is used for filling land depressions, disused quarries and clay pits.