Phosphorus-32,a $\beta$ ^- Emitter,is a Radioactive Isotope Used in Many Biomedical Applications

Phosphorus-32,a $\beta$ ^- emitter,is a radioactive isotope used in many biomedical applications.How much time has passed if the ratio of ³²S to ³²P is 4 to 5? (The half-life of phosphorus-32 is 14.3 days.)

A) 11.4 days
B) 16.7 days
C) 4.60 days
D) 12.1 days
E) 16.9 days