(A-D) Concave mirror is used in a solar furnace because it converges parallel rays of sunlight to a single point (focus),producing high heat.
$(b)$ Convex mirror is used as a side/rear-view mirror in vehicles because it provides a wider field of view and always forms a virtual,erect,and diminished image.
Concave mirror can form a magnified and virtual image when the object is placed between the pole $(P)$ and the focus $(F)$ of the mirror.
The ray diagram for the magnified and virtual image is as follows: When an object is placed between $P$ and $F$,the reflected rays appear to diverge from a point behind the mirror,forming a virtual,erect,and magnified image.