A woman drives a car. During her journey, she travels 20 minutes at a speed of 60 km/hr, another 30 minutes at a speed of 40 km/hr and 1 hour at a speed of 50 km/hr. The average speed of the car is:

A

540/11 kmph

B

630/11 kmph

C

100/11 kmph

D

90/11 kmph