When an object is placed infront of a convex mirror at a distance ' $u$ ' from the pole of the mirror such that the size of the image is ' $n$ ' times that of the object, then the object distance ' $u$ ' $=$

• A

  $\frac{\mathrm{f}}{\mathrm{n}^2}-\mathrm{nf}$
• B

  $\mathrm{nf}-\frac{\mathrm{f}}{\mathrm{n}}$
• Correct answer
  C

  $\mathrm{f}-\frac{\mathrm{f}}{\mathrm{n}}$
• D

  $\mathrm{f}+\frac{\mathrm{f}}{\mathrm{n}^2}$

Hence, the correct answer is option: 'C'.