Carbon-14 Has an Activity of 0

Carbon-14 has an activity of 0.25 Bq per gram of carbon for living organisms. The half-life of ¹⁴C is 5730 years. If a sample of charcoal from an archeological dig yields a ¹⁴C activity of 0.15 Bq per gram of carbon, how old is the material?

A) 6.6 × 10³ y
B) 5.1 × 10³ y
C) 4.2 × 10³ y
D) 1.7 × 10³ y
E) 1.4 × 10³ y