The correct answer is C. 8.
The Stefan-Boltzmann law states that the total energy radiated per unit surface area of a blackbody per unit time, is proportional to the fourth power of the absolute temperature. This means that if the absolute temperature of an object doubles, the maximum energy emitted goes up by a factor of 2^4 = 16. However, the maximum energy emitted is only a small fraction of the total energy radiated, so the actual increase in the total energy radiated is much less than 16.
The Stefan-Boltzmann law can be written as:
$$E = \sigma T^4$$
where $E$ is the energy radiated per unit surface area per unit time, $\sigma$ is the Stefan-Boltzmann constant, and $T$ is the absolute temperature.
If we double the absolute temperature, $T$, the energy radiated per unit surface area per unit time, $E$, increases by a factor of 2^4 = 16.
However, the maximum energy emitted is only a small fraction of the total energy radiated. The maximum energy emitted is given by the Planck function:
$$E_\text{max} = \frac{2hc^2}{\lambda^5}$$
where $h$ is Planck’s constant, $c$ is the speed of light, and $\lambda$ is the wavelength of the radiation.
The wavelength of the radiation is inversely proportional to the temperature, so if we double the absolute temperature, the wavelength of the radiation is halved. This means that the maximum energy emitted is also halved.
Therefore, if the absolute temperature of an object doubles, the maximum energy emitted goes up by a factor of 8.