The temperature of bodies $X$ and $Y$ vary with time as shown in the figure. If emissivity of bodies $X$ and $Y$ are $e_x$ and $e_y$ and absorptive powers are $A_x$ and $A_y$, (assume other conditions are identical for both), then

Assertion: Absorptive power is a dimensionless quantity and a body having low emissive power should have low absorptive power.

Reason: The ratio of emissive power to absorptive power is same for all bodies at a given temperature and is equal to the emissive power of a black body at that temperature.

Assertion: A body that is a good radiator is also a good absorber of radiation at a given wavelength.

Reason: According to Kirchhoff's law the absorptivity of a body is equal to its emissivity at a given wavelength.

In Ferry's black body, the area of black body is