How can I calculate a company's total amount of cash Payments?

These are given:

A company's Inventory balance at 12/31/07 was $200,000 and was $188,000 at 12/31/08. Its Accounts Payable balance at 12/31/07 was $80,000 and was $84,000 at 12/31/08, and its cost of goods sold for 2008 was $720,000.

The answers are:

A. $704,000.
B. $712,000.
C. $720,000.
D. $728,000.
E. $736,000.

Thank you.

I'm not sure but I think it's D. $728,000