A train overtakes two persons who are walking in the same direction in which the train is going, at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively. The length of the train is:

• ক 72 m
• খ 54 m
• গ 50 m ✅ সঠিক উত্তর
• ঘ 45 m