Speedometer device is used to measures:
A. Speed
B. Time
C. Distance travelled
D. Displacement

Hint: As we know that the speedometer reads the speed of the vehicle it is mounted on, in this question we will first learn about the basics of speedometer and then the speed. This information will help us find the answer to the above question.

Complete step by step answer:
A speedometer also called a speed meter is a gauge that measures and displays the instantaneous speed of a vehicle. It is mostly mounted on bikes, cars, scooters. We also know that the speedometer used to measure the speed of a vehicle and all the vehicles indicate speed in km/h.
Therefore, we can say that speedometer is used to measure speed in km/h

So, the correct answer is “Option A”.

Additional Information: We also know that a gauge is an instrument that measures and gives a visual display of the amount, level or contents of something.
It is also important to know that these speedometers are now universally fitted to motor vehicles; they started to be available as options in the early 20th century, and were available and used as standard equipment from about 1910 onwards. Many modern speedometers are electronic.
We already know the basic difference of speed and velocity i.e., speed is the measure of how fast an object can travel, whereas velocity tells us the direction of this speed. Speed is a scalar quantity that means it has only magnitude, whereas velocity is a vector quantity that means it has both magnitude and direction. The S.I unit of velocity is meter per second (m/sec).

Note: Here, it is important to remember most speedometers have a maximum limit up to 140-160 mph. We know that the S.I unit of speed is m/sec but the speedometer shows the value in km/h. Therefore, the question can be directly solved by having an idea of the unit of speed.