The correct answer is D. 75 kmph.
B-Class ODC is a type of freight train that is used to transport bulk commodities, such as coal, iron ore, and grain. It is a relatively slow train, with a maximum speed of 75 kmph. This is because it is designed to carry heavy loads, and it is important to keep the speed down to avoid damage to the track and the train itself.
A. 15 kmph is too slow for a B-Class ODC train. This would be the speed of a passenger train, or a very light freight train.
B. 25 kmph is still too slow for a B-Class ODC train. This would be the speed of a slow-moving truck.
C. 40 kmph is closer to the maximum speed of a B-Class ODC train, but it is still not quite right. This would be the speed of a medium-speed passenger train.
D. 75 kmph is the correct answer. This is the maximum speed of a B-Class ODC train.