You Need to Hold the Pressure of N₂O Gas in a Balloon

You need to hold the pressure of N₂O gas in a balloon constant overnight, so you place it in a glove box that may contain a variety of gases.With which gas should you fill the glove box?

A) air (~78% N₂ and 21% O₂)
B) O₂
C) Ar
D) N₂
E) CO₂