Carbon-14 decays by beta emission with a half life of 5,730 years. Assuming a particular object originally contained 6.5 micro grams of C-14 and now contains 0.76 micro grams of C-14, how old is the object?
a. 27,300 years
b. 18,000 years
c. 12,666 years
d. 10,992 years
e. 22,664 years