After Chemical Analysis, a Radioactive Sample Is Found to Contain

After chemical analysis, a radioactive sample is found to contain 1.00 g of francium to every 2.50 g of astatine, its daughter isotope. If the half-life of francium is 4.18 min, approximately how old is the sample?

A) 7.65 min
B) 7.56 min
C) 5.67 min
D) 5.76 min
E) 6.57 min