Narrowest part of esophagus is at?
Ans. is 'a' i.e., Cricopharyngeal sphincter * The narrowest part of esophagus is its commencement at the cricopharyngeal sphincter.
Cricopharyngeal sphincter
At the Aortic constriction
At the crossing of left principal bronchus
At the diaphragmatic opening
Oesophagus