d
Thrust $\mathrm{Th}=\mathrm{V} \sigma \mathrm{g}$
Vol. of body $V=\frac{(264-221) g}{1 \times g}=43 \mathrm{cc}$
volume of material
$=\frac{\text { mass of body }}{\text { density }}=\frac{264}{8.8}=30 \mathrm{cc}$
vol. of cavity $=(43-30) \mathrm{cc}=13 \mathrm{cc}$