Music appreciation a theme is a melodic idea that's a. of lesser importance than other musical ideas. b. a two-measure song. c. always in a minor key. d. stated and restated in different forms.

In my opinion, the correct answer is D. stated and restated in different forms. A theme isn't of lesser importance - on the contrary, it often forms the melodic spine of a work, e.g. a sonata or a symphony. It may recur many times throughout the work, in many different forms, with a changed tonality, another key, extended or shortened versions...