What Was Entailed in a Professor's Glossing of a Text

What was entailed in a professor's glossing of a text?

A) The professor read a passage from a book and then commented on it extensively.
B) The professor skimmed over the text to locate and study the essential arguments alone.
C) The professor read a book enough times so that they would have it memorized.
D) The professor had his class read the text to him and explain it by themselves.
E) The professor invited a member of the clergy to help explain the text to the class.