Answer :
D. The input rating of the furnace is determined as 100,000 BTU.
What is input rating?
Input power rating means the power, expressed in Watts or one of its multiples, for which the energy storage unit has been designed to operate at nominal conditions.
eff = (output rating / input rating) x 100%
80/100 = 80,000 BTU / input rating
0.8 = 80,000 BTU / input rating
input rating = 80,000 BTU/0.8
input rating = 100,000 BTU
Thus, the input rating of the furnace is determined as 100,000 BTU.
Learn more about input rating here: https://brainly.com/question/5027692
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