The mass is an example of

A. sacred music.
B. modern music.
C. electronic music.
D. Romantic music.

There is not enough information to answer this question accurately. "Mass" can refer to different things in music, such as the Catholic Mass (a sacred music genre) or a musical work titled "Mass" by a particular composer (which could belong to any of the listed genres).

The correct answer is D. Romantic music.