The correct answer is option 4: for no value of u.
This means that the statement in the question is incorrect. In reality, the image formed by a convex mirror of a real object is always smaller than the object, regardless of the value of u.
A convex mirror is a type of spherical mirror that curves outward. When light rays from an object pass through a convex mirror, they diverge or spread out. This causes the image formed by the convex mirror to appear smaller than the object.
The size of the image formed by a convex mirror is determined by the distance between the object (u) and the mirror`s focal point (f). However, regardless of whether u is less than, greater than, or equal to twice the focal length (2f), the image will always be smaller than the object.
Therefore, it is important to understand that the image formed by a convex mirror of a real object is always smaller, not larger, than the object.