Answer:
Magnification is the ratio of enlargement and reduction of an image
Step-by-step explanation:
Magnification is the way of enlarging the apparent size of an object. When the magnification of an object is less than 1 it shows reduction in size while when it is greater than 1, it shows enlargement in size. Mathematically, it is given by :

i.e.

Hence, the correct option is (c) " both a and b " i.e. " enlargement and reduction ".