In a normal individual, a tube with a transducer at its tip is swallowed and passed an unknown distance down the esophagus. Between swallows it records a pressure of 25 mm Hg. A small amount of water is swallowed. Within 2 seconds, the pressure falls to 5 mm Hg, where it remains until returning to its resting pressure 6 seconds later. In a patient with achalasia, the transducer is advanced to the same location. Between swallows, it records a pressure of 30 mm Hg. After swallowing, the pressure fails to decrease at all. In which of the following sites is the transducer most likely located?
(A) Esophageal body distal to the diaphragm
(B) Esophageal body proximal to the diaphragm
© Lower esophageal sphincter
(E) Upper esophageal sphincter