Concept:Chain surveying is best carried out on flat, open, and level ground.Explanation:Chain survey depends on measuring horizontal distance directly with a chain.Plain topography is flat and has no steep bends or contours that disturb chain measurement.Irregular slopes, rocky environments, and embarkment areas make accurate chaining difficult because the chain cannot lie straight and horizontal over such surfaces.Therefore, plain topography is the most suitable option for chain survey.Answer:D. Plain topography.