According to the author, you can save interest on a month-to-month basis by shuffling balance form home-equity lines to credit cards offering zero-interest deals only if________.
A.you could think creatively on the home-equity line
B.you replace the home-equity line with a fixed-rate second mortgage
C.you pay attention to the small print and shift money back at the right time
D.the mortgage rate is below 7.89 percent