Ahuman body that is performing light work generates about 400 btus of the body heat per hour while active. if an office that is 20 ft x 30ft x 10ft has 8 workers, how many btus per cubic foot do they produce in 3 hours(to the nearest tenth)

a)0.2 btus/ft3
b)0.6
c)1.5
d)2.9