mol of $O_2=\large\frac{6}{32}$
$\therefore $ No of molecules in $\large\frac{6}{32}$ moles of $O_2=\large\frac{6}{32} $$\times 6.022 \times 10^{23}$
Mol of $SO_2=\large\frac{6}{64} $ and number of molecules of
$SO_2=\large\frac{6}{64} $$\times 6.022 \times 10^{23}$
Thus number of molecules of $SO_2$ will be less than that of $O_2$
Hence c is the correct answer.