Suppose you have a \(1 \mathrm{~g}\) sample of \({ }^{226} \mathrm{Ra}\), half-life 1600 years. How long will it be until only \(0.1 \mathrm{~g}\) of radium is left? \(\begin{array}{llll}\text { A. } 1600 \mathrm{yr} & \text { B. } 3200 \mathrm{yr} & \text { C. } 5300 \mathrm{yr} & \text { D. } 16,000 \mathrm{yr}\end{array}\)