Answer:
Coolest star is corresponding to that graph which have maximum wavelength. so correct answer will be
In Graph A, the curve peaks at 800 nm, in the red section of the visible light spectrum.
Explanation:
As we know by Wein's Displacement law that
here it shows that
= wavelength corresponding to maximum intensity
T = temperature
so here if wavelength and temperature is inversely depends on each other so we can say if wavelength corresponding to maximum intensity is small then its temperature must be high.
In graph A wavelength is 800 nm
In graph B wavelength is 550 nm
In graph C wavelength is 450 nm
In graph D wavelength is 300 nm
so here coolest star must be corresponding to graph A