Final answer:
The number 125 in the equation B = 12.5(125 - n) represents the point at which the electric bill would be $0 if the museum uses 125 solar panels. It means the bill decreases by $12.5 for the installation of each additional solar panel.
Step-by-step explanation:
The best interpretation of the number 125 in the equation B = 12.5(125 - n) is that the monthly electricity bill for a museum decreases by $12.50 for each solar panel installed (option D). However, this question seems to mistakenly include $125 in the choices, where it should only refer to the number 125 in the equation. Nonetheless, the number 125 represents the baseline number of solar panels at which the electric bill would be $0. Therefore, for every solar panel used, the number of solar panels n is subtracted from 125, and the result is multiplied by $12.5 to find the monthly bill. This leads us to conclude that the electric bill decreases by 125 solar panels' worth of electricity savings for each additional solar panel added. Therefore, interpretation (A) is most accurate when we consider how the equation is structured.