A blue supergiant star has a radius of 7.4 × 10^10 m. The spherical surface behaves as a blackbody radiator. If the surface temperature is 2.4 × 10^4 K, what is the rate at which energy is radiated from the star?
2 × 10^3 J/s
4 × 10^19 J/s
2 × 10^32 J/s
3 × 10^33 J/s