According to the Stefan-Boltzmann law, which of the following statements expresses the radiative energy emitted by one square metre of an object?

a. It is equal to a constant multiplied by its temperature, raised to the negative third power.
b. It is equal to a constant multiplied by its temperature, raised to the second power.
c. It is equal to a constant multiplied by its temperature, raised to the fourth power.
d. It is equal to a constant multiplied by its temperature, raised to the tenth power.