b
\(\begin{array}{l}
Density\left( d \right) = \frac{{mass\left( M \right)}}{{volume\left( V \right)}} = \frac{M}{{{L^3}}}\\
\therefore Error\,in\,density,\,\frac{{\Delta d}}{d} = \frac{{\Delta M}}{M} + \frac{{3\Delta L}}{L}\\
= 1.5\% + 3\left( {1\% } \right) = 4.5\%
\end{array}\)