A wire is stretched 1 mm by a force $F$. If a second wire of same material, same length and 4 times the diameter of the first wire is stretched by the same force $F$, then the elongation of the second wire is

• A

  $\frac{1}{8} \mathrm{~mm}$
• B

  8 mm
• C

  16 mm
• Correct answer
  D

  $\frac{1}{16} \mathrm{~mm}$

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