A local car dealer is advertising a lease on a Ford Explorer. The upfront cost is $5000 with a monthly lease payment of $289. The cost equation is C = 5000 + 289x, where x is the number of payments. Which of the following statement is true?
A: C is an independent and x is a dependent
B; x is an independent and C is a dependent
C: 5000 is an independent and x is a dependent
D: 289 is an independent and 5000 is a dependent