An object is $10cm$ in front of a concave mirror which produces an upright image. The radius of curvature of the mirror is:

The correct option is B More than $20cm$
An erect image is formed by the concave lens when the object distance is smaller than the focal length of the mirror. In this case, the object is 10 cm in front of a concave mirror which produces an upright image. So, the focal length must be greater than 10 cm.
We know that, Radius of curvature is twice the focal length.