A fossilized animal that was killed by a volcanic eruption has 6.25 percent of its original amount of carbon-14 remaining; this radioisotope has a half-life of 5730 years. How long ago did the volcano erupt?
a)Â 34,380 years agob)Â 22,920 years agoc)Â 17,190 years agod)Â 9,168 years ago