A steel meter scale is to be ruled so hat millimeter intervals are accurate within about $5 \times 10^{-5}m$ at a certain temperature. The maximum temperature variation allowable during the ruling is: <br> (Coefficient of linear expansion of steel = $10 \times 10^{-6} K^{-1}$)

Question

( A ) $7^{\circ}$
( B ) $5^{\circ}$
( C ) $2^{\circ}$
( D ) $10^{\circ}$