The lower horizontal watershed starts at the umbilicus and follows the caudal limitation of the rib cage to the vertebral column, at the level of T12.

• A. True
• B. False
• C. Cannot determine
• D. Not applicable

Answer: (A)

In MLD, watershed boundaries mark where lymph drainage zones are separated and guide where to direct work. The lower horizontal watershed is defined as starting at the umbilicus and following the caudal limit of the rib cage to the vertebral column at the level of T12. The lower border of the rib cage indeed aligns with the T12 level, so tracing along that edge from the umbilicus to the back creates a consistent anatomical boundary between abdominal and lower trunk regions. This alignment helps therapists determine which lymphatic pathways and regional nodes to target for the lower trunk and pelvis. Therefore, the statement matches the standard landmark description, making it the best choice. Other options would contradict these fixed anatomical landmarks or rely on information not defined by the map.