A metal rod (Y= 2 x 10¹² dyne/sq. cm) of coefficient of linear expansion 1.6 x 10⁻⁵ per °C has its temperature raised by 20°C. The linear compressive stress to prevent the expansion of the rod is:
(a) 2.4 x 10⁸ dyne/sq. cm
(b) 3.2 x 10⁸ dyne/sq. cm
(c) 6.4 x 10⁸ dyne/sq. cm
(d) 1.6 x 10⁸ dyne/sq. cm