Charcoal Found Under a Stone at Stonehenge, England, Has a Carbon-14

Charcoal found under a stone at Stonehenge, England, has a carbon-14 activity that is 0.60 that of new wood. How old is the charcoal (The half-life of carbon-14 is 5,730 years.)

A) Less than 5,730 yr
B) Between 5,730 and 11,460 yr
C) Between 11,460 and 17,190 yr
D) More than 17,190 yr