Answer: D) Product lines.
A product line is a group of related products or services that are marketed and sold by a company under the same brand name. In this case, the major university is offering different types of education programs such as undergraduate studies, graduate studies, and professional programs, which are all related to education and are marketed and sold under the same brand name of the university. Therefore, the university's undergraduate studies, graduate studies, and professional programs can be considered as product lines within the university's product mix.
Explanation: