The correct answer is B) Check the hose and nozzle for clogs. In addition to weighing the cartridge, it is also important to check the hose and nozzle of a cartridge-operated dry chemical extinguisher to ensure they are not clogged. This is a key maintenance requirement to ensure the extinguisher will function properly when needed. The other answer choices are incorrect because: A) Weighing the powder is not a required maintenance item for this type of extinguisher. C) Discharging a small amount is not necessary as part of routine maintenance. D) Checking the external pressure gage is not a requirement for this type of extinguisher.