Which NSTM contains information on the repair and care of labyrinth packing?

The correct answer is B, as NSTM 231 specifically addresses the repair and care of labyrinth packing. Labyrinth packing is a crucial component in various machinery that helps prevent leaks and maintain performance. By referring to NSTM 231, personnel can find detailed guidance on the proper maintenance practices, installation procedures, and troubleshooting techniques related to labyrinth packing. This ensures that the packing remains effective in sealing and prolongs the life of the equipment it serves.

The other NSTM references provided focus on different aspects of machinery or systems; for example, NSTM 200 typically deals with general machinery maintenance, while NSTM 250 and NSTM 300 cover other specific topics or systems in naval operations. Thus, they do not provide the specialized information necessary for dealing with labyrinth packing specifically.