A furnace made of a red brick wall of thickness 0.5 mtr. and conductivity 0.7 W/mK is replaced by alternate material of conductivity 0.14 W/mK. For the same heat loss and
temperature drop, required thickness of alternate material will be

A

0.2 mtr

B

0.1 mtr

C

0.3 mtr

D

0.4 mtr