Which of these people repaid his loan at a variable interest rate?

A.
Andre, who made monthly payments of $57 for one year
B.
Gary, who paid $37 each month for the first six months and $67 for the next six months
C.
Dean, who repaid the full amount of the loan in one installment

Question

Which of these people repaid his loan at a variable interest rate?

A. 
Andre, who made monthly payments of $57 for one year
B. 
Gary, who paid $37 each month for the first six months and $67 for the next six months
C. 
Dean, who repaid the full amount of the loan in one installment

Vocaloid · Answer

notice how one person didn't pay any interest at all by paying the full amount
another person had a constant interest rate since they paid the same amt. each month
yet another person must have had a variable interest rate since they paid diff. amounts each month

identify the variable interest rate off this information