A student goes to school at the rate of km/hr and reaches 6 minutes late. If he travels at the speed of 3 km/hr, he reaches 10 minutes earlier. The distance of the school is :

[A]4 km

[B]10 km

[C]20 km

[D]45 km

**4 km**

Distance of school = x km

Difference of time = 16 minutes

Hence option [A] is correct answer.