The correct answer is: A. Is inversely proportional to the temperature.
Wein’s displacement law states that the wavelength at which a black body emits the most radiation is inversely proportional to its temperature. This means that as the temperature of a black body increases, the wavelength of the light it emits decreases.
The law can be expressed mathematically as:
$$\lambda_{max} = \frac{b}{T}$$
where $\lambda_{max}$ is the wavelength of maximum emission, $b$ is a constant called Wein’s displacement constant, and $T$ is the temperature of the black body.
Wein’s displacement law is a consequence of the Planck radiation law, which describes the spectral radiance of a black body as a function of wavelength and temperature. The Planck radiation law can be derived from the laws of thermodynamics and electromagnetism.
Wein’s displacement law has a number of important applications. For example, it can be used to estimate the temperature of stars and other astronomical objects. It can also be used to design and optimize thermal systems.
The other options are incorrect because they do not accurately reflect the relationship between wavelength and temperature as described by Wein’s displacement law.