Step 1: Understanding the Concept:
"Pyloric" refers to the pylorus, the funnel shaped end of the stomach that narrows before opening into the small intestine. Any answer choice must place the sphincter right at that narrowing.
Step 2: Key Formula or Approach:
Walk through the gut in order: mouth, esophagus, stomach, duodenum, rest of small intestine, cecum, large intestine. Each junction between two of these parts is guarded by one specific valve or sphincter, so matching "pyloric" to its location rules out all the other junctions.
Step 3: Detailed Explanation:
The stomach ends at a narrow region called the pylorus, and the ring of smooth muscle there is the pyloric sphincter. Past the pylorus lies the duodenum, the first 25 cm or so of the small intestine, where the sphincter releases chyme in small amounts so it does not overwhelm the duodenum. The mouth-esophagus junction, the esophagus-stomach junction, and the ileum-large intestine junction each have their own separate valve, none of which is called "pyloric".
Step 4: Final Answer:
The pyloric sphincter lies between the stomach and the duodenum, so the correct choice is (B) stomach and duodenum.