Ina furnace madeof bricks,
Inside heat transfer coefficient = $$35 W/m^2 K$$
Outside heattransfér coefficient = $$25 W/m^2 K $$
Thermal conductivity of bricks (15 cm thick) = $$0. 15 W/m K$$
The overall heat transfer coefficient $$(in W/m^2 K)$$ will be closer to the

A

Inside heat transfer coefficient

B

Outside heat transfer coefficient

C

Thermal conductivity of bricks

D

Heat transfer coefficient based on the thermal conductivity of the bricks alone.