A steel rod at 25°C is observed to be 1 m long when measured by another metal scale which is correct at 0°C. The exact length of steel rod at 0°C is (αₛₜₑₑₜ = 12 × 10ˉ⁶/°C, αₘₑₜₐₗ = 20 × 10ˉ⁶/°C)
a. 1.00002 m
b. 1.0002 m
c. 0.998 m
d. 0.9998 m