A thief running at speed of ‘x’ km/h is chased by a policeman running at a speed of 10 km/h. If the thief is ahead by 100 metres, the policeman catches the thief after 3 minutes. At what speed is the thief running (‘x’ being the unknown speed)?

A

4 km/h

B

8 km/h

C

10 km/h

D

6 km/h