A structural steel rod has a radius \( r(=10 \mathrm{~mm}) \) and a...

A structural steel rod has a radius \( r(=10 \mathrm{~mm}) \) and a length \( l(=1 \mathrm{~m}) \). When a force \( F(=100 \mathrm{kN}) \) is applied, it stretches it along its length. Young's modulus of elasticity of the structural steel is \( 2 \cdot 0 \times 10^{11} \mathrm{Nm}^{-2} \).
What is the elongation produced?
(A) \( 1.59 \mathrm{~mm} \)
(B) \( 2.32 \mathrm{~mm} \)
(C) \( 0.159 \mathrm{~mm} \)
(D) \( 3.18 \mathrm{~mm} \)