How did composers in the Classical period make their music interesting despite its relatively limited harmonic vocabulary?

Popular and folk music both tend to feature works that are immediately appealing and "understandable", even to people who have little musical training or knowledge. This immediate appeal usually comes from an underlying simplicity; folk and popular musics often feature short or repetitive forms, driving rhythms that encourage movement and dance, and melodies and harmonies that are comfortably within their traditions. One does not need to study music to appreciate a popular song, and in fact, studying that song would probably not increase one's appreciation of it very much.

Explanation:

c. shubert i think : )