What defines an opera in a performance context?

An opera is defined in a performance context as a play set to music. This form of art combines a dramatic narrative with music, where the story is conveyed primarily through vocal performance, supported by orchestral accompaniment. In opera, characters express their emotions and advance the plot through sung dialogue (often called arias, recitatives, and ensembles), distinguishing it from a musical where spoken dialogue can be more prominent.

The incorporation of elements like scenery, costumes, and staging further enhances the theatrical experience, contributing to the unique identity of opera as a genre that blends drama and musical performance. This complexity and interrelation of narrative and music are what set opera apart within the broader category of musical performances.

In contrast, the other options do not capture the essence of opera. A musical without vocals, a dance performance with a solo artist, or a piece featuring only orchestral music lack the essential elements of sung storytelling and theatrical presentation that define opera.