The Diagram Shows Manometric Recordings from a Patient Before and After

Multiple Choice

The diagram shows manometric recordings from a patient before and after pelvic floor training. A balloon placed in the rectum was inflated (arrows) and deflated repeatedly. Tracing Z is a manometric recording obtained from the external anal sphincter before and after pelvic floor training. Which of the following best describe the origin of tracing X?

A) Distal rectum
B) Ileocecal valve
C) Internal anal sphincter
D) Lower esophageal sphincter
E) Proximal rectum