When the total emissive power E of an ideal blackbody is plotted on the y-axis against T4 on the x-axis, which description of the resulting graph is correct?
a) A straight line cutting the y-axis at a positive intercept
b) A straight line passing through the origin with slope equal to a constant
c) A parabola opening upward
d) A straight line passing through the origin with slope 4σ