Which of the following is a vector quantity?
a.Speed
b.Displacement
c.Mass
d.Time

Hint: In this question, we will one by one see the basic definition of each given physical term; this will help us to get our correct answer easily. Further, we will see the basic difference between speed and velocity in terms of magnitude and direction, for our better understanding.

Complete answer:
As we know that the speed is a scalar quantity which means it has only magnitude not direction whereas, the average velocity is a vector quantity.
As we know displacement can be defined as the shortest distance between starting and final point which prefers a straight-line path over any curved path of an object or body. Also, we know that displacement is a vector quantity.
Now, we see that mass is a fundamental property of all matter. We can also say that mass is a quantitative measure of inertia. Mass is measured in kilograms. Since, mass has only magnitude, so mass is a scalar quantity.
Also, we know, time is defined by its measurement. Time is what a clock reads. In classical and non- relativistic physics, it is a scalar quantity. The S.I unit of time is second.

Therefore, the correct option is b) i.e., displacement is a vector quantity.

Additional information:
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 gives 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:
We should remember that any physical quantity which has magnitude is a scalar quantity whereas; if any object has magnitude and direction then the object is called vector quantity. Also, we can get the answer to this question easily if we know the basic definition of each given term.