Magnification produced by a concave lens is always: 

The ability of a lens to enlarge an object's picture is measured by its magnification (m). The ratio of the image's height to the object's height is how a lens' magnification is stated. Mathematically, $m=\frac{Y}{X}$, where Y is the picture height and X is the object height.
The magnification of the lens is positive if the height of the image it creates is more than the height of the object; it is negative if the height of the image it creates is less than the height of the item. The question concerns the magnification that a concave lens produces, for which we need to be aware of the concave lens's characteristics.
A lens with at least one curved inside surface is said to be concave. It is a diverging lens because when light is projected upon it, the light rays that refract through the curved surface spread apart.
An upright, virtual, and scaled-down picture of the object's side appears when it is placed in front of a concave mirror. Because the size of the picture created is smaller than that of the item, the resultant magnification is less than 1.

$m_{\text{concave }}<1$

Hence, the correct answer is option A.