Final answer:
The superior end of the sacrum articulates with the 5th lumbar vertebra, serving as a crucial connection point within the vertebral column and supporting body weight.
Step-by-step explanation:
The superior end of the sacrum articulates with the D) 5th lumbar vertebra. The sacrum itself is a triangular-shaped bone that forms the back portion of the pelvic girdle and is made by the fusion of five sacral vertebrae. At its superior end, it connects with the last lumbar vertebra, L5, supporting a significant amount of body weight and playing a crucial role in the structure of the vertebral column. The inferior tip of the sacrum articulates with the coccyx, or tailbone, which is not weight-bearing in a standing position but may support some weight when sitting.