A sealed $29-$m$3$ tank is filled with $9000$ moles of oxygen gas $($O$2)$ at an initial temperature of $270$ K$.$ The gas is heated to a final temperature of $400$ K$.$ The ATOMIC mass of oxygen is $16\mathrm{.}0$ g$/$mol$,$ and the ideal gas constant is R $=8\mathrm{.}314$ J$/$mol$$K $=0\mathrm{.}0821$ L$$atm$/$mol$$K$.$ The initial pressure of the gas is closest to

$0\mathrm{.}61$ MPa$\mathrm{.}0\mathrm{.}70$ MPa$\mathrm{.}0\mathrm{.}88$ MPa$\mathrm{.}0\mathrm{.}79$ MPa$\mathrm{.}0\mathrm{.}51$ MPa.