Which of the following represents the correct formula for the magnification of a lens?

Magnification is defined as the ratio of the height of the image to the height of the object or the ratio of the image distance to the object distance.
It is often indicated by the letter "m".

$\mathrm{m}= \frac{\mathrm{Height} \mathrm{of} \mathrm{image} \left(\mathrm{I}\right)}{\mathrm{Height} \mathrm{of} \mathrm{object} \left(\mathrm{O}\right)}$       OR

$\mathrm{m}= \frac{\mathrm{Distance} \mathrm{of} \mathrm{image} \left(\mathrm{v}\right)}{\mathrm{Distance} \mathrm{of} \mathrm{object} \left(\mathrm{u}\right)}$