What is the average value of the magnitude of the Poynting vector at 1 metre from a 100-watt light bulb radiating in all directions?

What is the average value of the magnitude of the Poynting vector at 1 metre from a 100-watt light bulb radiating in all directions?
A)1 W/m2
B)4 W/m2
C)2 W/m2
D)8 W/m2
E)12 W/m2