A Student Is Sleeping Under a Small Goose-Down Comforter That

A student is sleeping under a small goose-down comforter that has thermal conductivity of 0.025 W/m °C. The thickness of the down comforter is 5.0 cm and the area of the comforter is 2.0 m². If the temperature difference between inside of the comforter and the outside of the comforter 40 °C, then what is the rate of heat flow through the comforter?

A) 10 W
B) 20 W
C) 30 W
D) 40 W
E) 50 W