Why is the C-14/C-12 ratio used to date once-living organisms? O A. The amount of C-12 changes when an organism dies.
O B. An organism stops taking in carbon when it dies.
O C. C-12 becomes radioactive when an organism dies.
O D. The half-life of C-14 changes when an organism dies.

Why is it important for scientists to review and repeat the work of other scientists? 1.a scientific theory must be tested three times before it is proven. 2.the scientific method only applies to repeated experiments. 3.an experiment may have had errors that the scientists didn't recognize. 4.the results of individual scientists may be influenced by bias. 5.an experiment must be performed twice before the data can be analyzed.