The generator initially provided \(125 \mathrm{~W}\) of power. If you assume that the power of the generator is proportional to the activity of the plutonium, by approximately what percent did the power output decrease over the first two years of the rover's mission?
A. \(1.5 \%\)
B. \(2.0 \%\)
C. \(2.5 \%\)
D. \(3.0 \%\)
E. \(3.5 \%\)

The Curiosity rover sent to explore the surface of Mars has an electric generator powered by heat from the radioactive decay of \({ }^{238} \mathrm{Pu}\), a plutonium isotope that decays by alpha emission with a half-life of 88 years. At the start of the mission, the generator contained \(9.6 \times 10^{24}\) nuclei of \({ }^{238} \mathrm{Pu}\).