The uranium in the earth's crust is \(0.7 \%{ }^{235} \mathrm{U}\) and \(99.3 \%{ }^{238} \mathrm{U}\). Two billion years ago, \({ }^{235} \mathrm{U}\) comprised approximately \(3 \%\) of the uranium in the earth's crust. This tells you something about the relative half-lives of the two isotopes. Suppose you have a sample of \({ }^{235} \mathrm{U}\) and a sample of \({ }^{238} \mathrm{U}\), each with exactly the same number of atoms.

A. The sample of \({ }^{235} \mathrm{U}\) has a higher activity.

B. The sample of \({ }^{238} \mathrm{U}\) has a higher activity.

C. The two samples have the same activity.