The correct option is C 16 km/min
Given,
A car covers 20 km in 40 mins.
∴ in one minute, it will cover
=2040 = 12 km/min
Again, a bike covers 20 km in 30 mins.
∴ in one minute, it will cover
=2030 = 23 km/min
So, the difference in their rate or speed
= 23−12 = 16 km/min