Hargren Publishing offers its Accounting textbooks as e-texts through its online homework management system. Purchase of an access code provides the student with access to the e-text and online learning materials for six months. During that time, students have access to updates to the text and learning materials. Hargren should recognize revenue for purchases of access codes: a. at the end of the six-month access period
b. when they occur.
c. over the six-month period during which the customer has access.
d. at the beginning of the semester In which the student will use the access code.