Final answer:
A hard stop during probing, saline not reaching the throat, and positive regurgitation are indicative of Achalasia, which is a dysfunction of the lower esophageal sphincter. Option 4.
Step-by-step explanation:
When probing causes a hard stop, saline does not reach the throat, and regurgitation is positive, this is strongly indicative of Achalasia option 4. Achalasia is a condition where there is a dysfunction of the lower esophageal sphincter (LES), which leads to difficulty in swallowing, as the sphincter fails to relax properly to allow food into the stomach. This results in food getting stuck in the esophagus, and sometimes regurgitation of the food due to the inability of the esophagus to propel the food downward effectively. The failure of saline to reach the throat suggests a blockage at the level of the LES. Additionally, a hard stop during probing implies that there is resistance at the LES, which is characteristic of achalasia.