Correct option is C. Both A and B
Convex mirrors are used as rear view mirrors in vehicles because of the following reasons.
(1) A convex mirror always produces a virtual and erect image of the objects.(2) The image of the object formed by a convex mirror is greatly diminished in size. Consequently the driver is able to view much larger area of the traffic behind him than would be possible if a plane mirror were used instead of a convex mirror.