A furnace is made of a red brick wall of thickness 0.6 m and conductivity 0.8 W/m K. For the same heat loss and temperature drop, this can be replaced by diatomite earth of
conductivity 0.16 W/m K_ and thickness of --------

A

0.55 m

B

0.12 m

C

1.25 m

D

0.50 m