Image C is a convex lens.An optical lens is made up of two spherical surfaces is convex lens.Its surfaces are curved outwards.
An optical lens is made up of two spherical surfaces is convex lens The lens is called a biconvex lens or simply convex lens if those surfaces are curved outwards.
Converging lens is another name for it. It's because it brings all the light rays that are parallel to the primary axis together at the focus point (F).
The picture created by a convex lens is always real and inverted. The produced image is virtual and erect when the item is positioned between the focus and the optical center of the lens.
Hence image C is a convex lens.
To learn more about the convex lens refer to the link;
https://brainly.com/question/1604692
