A train overtakes two girls walking along a railway track. The first girl walks at 9 km/hr. The other girl walks at 10.8 km/hr. The train needs 16.8 and 17 seconds respectively to overtake them. What is the speed of the train if both the girls are walking in the same direction as the train?

(A) 23 m/s
(B) 34 m/s
(C) 45 m/s
(D) 50 m/s