Final answer:
The nurse should wear a mask when administering medication to a client with active tuberculosis.
Step-by-step explanation:
The nurse should wear a mask when administering medication to a client with active tuberculosis. Wearing a mask helps to prevent the spread of tuberculosis bacteria through respiratory droplets. Tuberculosis is primarily transmitted through the air, so wearing a mask helps to protect both the nurse and other individuals in the vicinity from inhaling the bacteria.