Radioactive Isotopes Are Used in Dating Materials from the Distant $\pm$

Radioactive isotopes are used in dating materials from the distant past.Which of the following statements about radioactive dating techniques is true?

A) It gives the general ages of rock strata.( $\pm$ 1 million years) .
B) It gives exact ages of rock strata.( $\pm$ 1 year) .
C) It uses a technique in which the degree of radioactive decay is measured, the younger the rock the more radioactive decay.
D) It uses a technique in which the degree of radioactive decay is measured, the older the rock the more radioactive decay.