Concept:A map scale gives the ratio between a distance on the map and the actual distance on the ground.Formula used:Ground distance = map distance × scale denominator; 1 km=100,000 cmSolution:The scale is 1:200,000, so 1 cm on the map equals 200,000 cm on the ground.Actual distance =2×200,000=400,000 cmIn kilometres: 400,000÷100,000=4 kmAnswer:Option D (4 km)