How Much Compressional Stress Builds Up in a Thick Aluminum $\alpha$

Multiple Choice

How much compressional stress builds up in a thick aluminum bar held between 2 immovable walls if the temperature increases by 20. C°?
( $\alpha$ = 24. × 10^-6 C^-1, Y = 7 × 10¹⁰ N/m²)

A) 34. × 10⁷ N/m²
B) 34. × 10⁸ N/m²
C) 34. × 10⁶ N/m²
D) 34. × 10⁴ N/m²
E) 34. × 10⁵ N/m²