oral surgeon put his finger on the nose of the patient and the patient asked to blow.. anterior extention of posterior palatal seal

oral surgeon put his finger on the nose of the patient and the patient asked to blow.
This done to check:
a. anterior extention of posterior palatal seal.***
b. lateral extension of posterior palatal seal
c. posterior extension of posterior palatal seal.
d. glandular opening.

Land marks for posterior palatal seal:
The posterior outline: is formed by the "Ah" line or vibrating line and passes through the two pterygomaxillary (hamular) notchs and is close to the fovea palatine.
The anterior outline: is formed by the "blow" line and is located at the distal extent of the hard palate.