A second order reaction $2\mathrm{A}\to \mathrm{P}$ ($-d[\mathrm{A}]/dt=k[\mathrm{A}{]}^2$) has $k=2.0\times 10^{-3}\mathrm{L}\mathrm{mo}{\mathrm{l}}^{-1}{\mathrm{s}}^{-1}$ at $300\mathrm{K}$ and $E_a=60\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ (independent of temperature). Take $R=8.314\mathrm{J}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}$. The half-life at $320\mathrm{K}$ for $[\mathrm{A}{]}_0=0.50\mathrm{mol}{\mathrm{L}}^{-1}$ is closest to

1. A$1000\mathrm{s}$
2. B$222\mathrm{s}$
3. C$77\mathrm{s}$
4. D$111\mathrm{s}$