Nitrous Oxide, N₂O, Decomposes on Metal Surfaces Readily at High $\rarr$

Nitrous oxide, N₂O, decomposes on metal surfaces readily at high temperatures following first-order kinetics for the equation:
2 N₂O (g) $\rarr$ 2 N₂ (g) + O₂ (g)
The following data are obtained for a reaction at 850°C: What was the initial concentration of N₂O (t = 0) ?

A) 0.0885 M
B) 0.0940 M
C) 0.101 M
D) 0.112 M
E) 0.123 M