The Important Breakthrough in Theoretical Physics That Was First Suggested $\sigma$

Multiple Choice

The important breakthrough in theoretical physics that was first suggested by Planck to explain the shape of the spectrum of a hot body was the

A) discovery of the formula F = $\sigma$ T⁴, which can be used to calculate the total energy flux emitted by the hot body over all wavelengths.
B) idea that light traveled at a constant speed, whatever the speed of the source.
C) idea that light is a form of electromagnetic energy transmitted at a constant speed and that there is a continuous spectrum of electromagnetic waves from gamma rays to radio waves.
D) concept that electromagnetic energy was emitted in small packets, or quanta.