A metal rod y = 2x10¹² dyne cm⁻² of coefficient of linear expansion 1.6x10⁻⁵ per •= C has its temperature raised by 20°C. the linear compressive stress to prevent the expansion of the rod is
A. 2.4×10⁸dyne/(cm)⁻²
B. 3.2×10⁸dyne/(cm)⁻²
C. 6.4×10⁸dyne/(cm)⁻²
D. 4.6×10⁸dyne/(cm)⁻²