Which of the following laws of chemical combinations is satisfied by the figure?

According to Gas Lussac's law of gaseous volume, when gases combine or are produced in a chemical reaction, they do so in simple ratio by volume, provided all gases are at same temperature and pressure.
$\underset{2 \mathrm{vol}}{2{\mathrm{H}}_2}+\underset{1 \mathrm{vol}}{{\mathrm{O}}_2}\to \underset{2 \mathrm{vol}}{2{\mathrm{H}}_2\mathrm{O}}$