In the aircraft propellers

the propulsive matter is ejected from within the propelled body
the propulsive matter is caused to flow around the propelled body
its functioning does not depend upon the presence of air
none of the above
✅ The correct answer is option A.

Fourier’s law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)

✅ The correct answer is option A.