You insulate your medium-sized attic with insulation with R=10. Which of the following sets of estimates is most reasonable?

A. The attic is 150 sq ft, the temperature difference on average is 5 degrees C, and electricity costs 1 cent per kWh.

B. The attic is 15,000 sq ft, the temperature difference on average is 10 degrees F, and electricity costs $10 per kWh.

C. The attic is 150 sq ft, the temperature difference on average is 5 degrees F, and electricity costs $1 per kWh.

D. The attic is 1500 sq ft, the temperature difference on average is 50 degrees F, and electricity costs 1 cent per kWh.

E. The attic is 1500 sq ft, the temperature difference on average is 10 degrees F, and electricity costs 10 cents per kWh.