Sita and Geeta start at same the time to ride from place A to place B, which is 90 km away from place A. Sita travels 3 km per hour slower than Geeta. Geeta reaches place B and at once turn back, meeting Sita 15 km from place B. Geeta's speed (in km/h) is:

A

9

B

6

C

7.5

D

10.5