Step 1: Formula for density.
\[
\rho = \frac{m}{V}
\]
Step 2: Volume of sphere.
\[
V = \frac{4}{3}\pi r^3
\]
Thus,
\[
\rho \propto \frac{m}{r^3}
\]
Step 3: Percentage error relation.
\[
\frac{\Delta \rho}{\rho} = \frac{\Delta m}{m} + 3\frac{\Delta r}{r}
\]
Step 4: Substitute given errors.
\[
= 3\% + 3 \times 2\%
\]
Step 5: Calculate.
\[
= 3\% + 6\% = 9\%
\]
Step 6: Final conclusion.
\[
\boxed{9\%}
\]
Hence, correct answer is option (D).