Distance covered per unit of time is called what.

Are these your choices?

a) acceleration c) inertia
b) velocity d) speed

What do YOU think the answer is?

its either speed or velocity

http://www.physicsclassroom.com/CLASS/1DKin/u1l1d.cfm

for speed you only need a speedometer.

for velocity you need a speedometer and a compass.

Distance covered per unit of time is called speed. Speed is a measure of how quickly an object moves from one place to another. To calculate speed, you typically divide the distance traveled by the time it takes to travel that distance. The formula for speed is:

Speed = Distance / Time

For example, if you travel 100 kilometers in 2 hours, your speed would be:

Speed = 100 km / 2 hours
Speed = 50 km/h

So, in this case, your speed would be 50 kilometers per hour.