A man rows from A to B (upstream) and B to A ( downstream) in 12 hours. The distance between A and B is 240 km. The rime taken by the man to row 6 km downstream is identical to the tin1e taken by him to row 4 km upstream. What is the speed of the stream?

A

$$\frac{50}{3}$$ km/h

B

$$\frac{35}{3}$$ km/h

C

$$\frac{46}{3}$$ km/h

D

$$\frac{25}{3}$$ km/h