Harry Took a Series of Education Classes to Learn How

Harry took a series of education classes to learn how to make minor repairs to his car and other types of gasoline-powered engines. When he completed the course, he was given a certificate of completion to

A) emphasize a relationship-marketing strategy.
B) serve as a tangible reminder of the course and to overcome the inseparability problem of services.
C) make the course seem more homogenous with other learning experiences.
D) serve as a reminder of the simplicity of the course undertaken, and the intangible benefits gained by fixing one's broken down car oneself.