GRE Reading Comprehension: Princeton-GRE阅读Princeton - 15GZF4FHHGTZOJJSC$

The author suggests that the burning of fossil fuels has had which of the following effects on the efficacy of carbon dating techniques? A. It may increase the carbon-isotope mix of the object being dated. B. It may make items subjected to carbon dating appear to have died later than is the case. C. It may tilt the fragile equilibrium activity of living matter.