All the options involve multiplication or division. The number of significant numbers in multiplication and division is the same as the one with less number of significant figures.
So:
[tex]20.947cm\times82.cm=1717.654cm^2=1.717654\times10^3cm^2\approx1.7\times10^3cm^2[/tex][tex]192.1g\div38.2mL=5.0287\ldots\frac{g}{mL}\approx5.03\frac{g}{mL}[/tex][tex]372.0mol\div0.75L=496\frac{mol}{L}=4.96\times10^2\frac{mol}{L}[/tex]
