Change in the tension $F= YA \;\alpha\; \Delta T$
$Y$- Young's modulus
$\Delta T$- change in temperature
$A$- area of cross - section
$F=(2.0 \times 10^{11})(1.1 \times 10^{-5}) \times 2 \times 10^{-6} \times 20$
$\qquad=88N$
Hence a is the correct answer