Concept:The length of River Ofon is measured along its winding course on the map by comparing it with the given linear scale.Explanation:Carefully trace the entire curved path of River Ofon using a thread or the edge of a paper strip.Mark the start and end points on the thread.Place this marked thread along the scale bar drawn below the map.Read the distance where the end point falls on the scale.The traced path of River Ofon matches approximately 16.5km on the scale.Answer:B. 16.5km
