Final answer:
The velocity of the car is 4 m/s.
Step-by-step explanation:
The velocity of the car can be found by dividing the displacement by the time taken. In this case, the car starts at position 10 meters and finishes at position 30 meters in 5 seconds. The displacement is therefore 30 - 10 = 20 meters. Dividing the displacement by the time gives us 20 / 5 = 4 meters per second. Therefore, the velocity of the car is 4 m/s, which corresponds to option a).