Radioactive Decay of Carbon 14

Years since death C14 atoms remaining per 1.0 x 108 C12 atoms
0 10,000
5,700 5,000
11,400 2,500
17,100 1,250
22,800 625
28,500 312
34,200 156
39,900 78
45,600 30
51,300 20
57,000 10
62,700 5
68,400 2

How old is a bone in which the Carbon-14 in it has undergone 3 half-lives?

A. 11,400

B.17,100

C. 34,200

D. 57,000

Please hurry I have a test