The distance between two stations A and B is 700 km. A train covers the journey from A to B at a speed of 80 km/h and
returns back to A with a uniform speed of 65 km/h. The average speed of train during the whole journey, is closest to:

A

74 km/h

B

71.72 km/h

C

72.7 km/h

D

70.73 km/h