At $27^\circ$C, five identical rigid $\pu{2.0 L}$ vessels are filled with $\ce{N2(g)}$. Four of the five vessels also contain a $0.050$ mol sample of $\ce{NaHCO3(s)}$, $\ce{NaBr(s)}$, $\ce{Cu(s)}$, or $\ce{I2(s)}$, as shown in the diagram below. The volume taken up by the solids is negligible, and the initial pressure of $\ce{N2(g)}$ in each vessel is $\pu{720 mm Hg}$. All four vessels are heated to $127^\circ$C and allowed to reach a constant pressure.

At $127^\circ$C, the pressure in vessel 1 is found to be higher than that in vessel 2. Which of the following reactions bests accounts for the observation?

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For the vessel to increase in pressure, the number of gas molecules must have increased over the course of the reaction.

In the first two equations, the reactions do not involve gas products.

Although the last choice shows that gas molecules are being formed, the same number of gas molecules are being removed from the vessel as reactants.