Answer:
c. $25,000 
Step-by-step explanation:
For determining the original principal amount we have to applied the Present value formula which is to be reflected in the spreadsheet below:
Given that, 
Future value = $0
Rate of interest = 8% 
NPER = 5 years 
PMT = $6,260.96
The formula is shown below: 
= -PV(Rate;NPER;PMT;FV;type) 
So after applying the above formula, the principal amount i.e present value is $24,998.20 which is approx $25,000