A cold storage chamber is constructed with $10 \mathrm{~mm}$ mortar, $200 \mathrm{~mm}$ brick, $100 \mathrm{~mm}$ insulation and $5 \mathrm{~mm}$ wood-board having thermal conductivities of 0.8,1.5,0.025 and $0.2 \mathrm{~W} \mathrm{~m}^{-1} \mathrm{~K}^{-1},$ respectively. The resistance of $4 \mathrm{~K} \mathrm{~m}^{2} \mathrm{~W}^{-1}$ is offered by
(A) mortar
(B) brick
(C) insulation
(D) wood-board
A cold storage chamber is constructed with $10 \mathrm{~mm}$ mortar, $200 \mathrm{~mm}$ brick, $100 \mathrm{~mm}$ insulation and $5 \mathrm{~mm}$ wood-board having thermal conductivities of 0.8,1.5,0.025 and $0.2 \mathrm{~W} \mathrm{~m}^{-1} \mathrm{~K}^{-1},$ respectively. The resistance of $4 \mathrm{~K} \mathrm{~m}^{2} \mathrm{~W}^{-1}$ is offered by
(A) mortar
(B) brick
(C) insulation
(D) wood-board