Why do we prefer a convex mirror as a rear-view mirror in the vehicles?

Hint: Discuss the properties of a concave mirror and understand how these properties benefit us when using a convex mirror as a rear view mirror. One of the properties is that a convex mirror always forms a virtual and diminished image of an object in front of it.

Complete step-by-step solution:
When driving on a road, we have to be aware of the vehicles behind us. For this purpose, a mirror is attached to the vehicle. The view is called rearview. Hence, the mirror is called a rearview mirror. Mostly, a convex mirror is preferred as a rearview mirror.
Let us first discuss why a convex mirror is used as a rearview mirror.
A convex mirror is a diverging mirror. Hence, it diverges the light rays that fall on it. As a result, the image formed due to this mirror is always a virtual mirror. This means that the image can be inside the mirror. The virtual image formed is always erect.
Then one may say that we can use a plane mirror too since the image formed by a plane mirror is also inside the mirror.
A convex mirror forms a diminished image. Due to the diminished size of the images, we get to see more area behind us than that of a plane mirror.
Therefore, a convex mirror increases our field of view.
In addition, the images are nearer than the actual distance of the object from us. Since the objects appear nearer, far away objects can be noticed easily.
Due to the discussed advantages of a convex mirror, it is preferred as a rearview mirror.

Note: The one more spherical mirror that we know of is a concave mirror. Let us discuss why a concave mirror cannot be used as a rearview mirror.
A concave mirror may form a virtual image or a real image depending on the distance of the object from the mirror. When a real image is formed, we cannot see the image inside the mirror as the image is formed outside the mirror.
That is why a concave mirror is not used as a rearview mirror.