Which is the proper method of determining whether a portable CO2 fire extinguisher needs recharging?

A
Check the tag to see when the extinguisher was last charged.
B
Release a small amount of CO2; if the CO2 discharges, the extinguisher is acceptable.
C
Weigh the extinguisher and compare the weight against that stamped on the valve.
D
Recharge the extinguisher at least once each year.
E