The dominant instrument in music since the nineteenth century is the

The dominant instrument in music since the nineteenth century is the pianoforte, or simply, the piano.
Although it was widely used ever since it was created in the early 18th century, it didn't reach its peak until the nineteenth century when many composers used this instrument for their compositions. Until this very day, it remained the most popular instrument used in music.

The answer is a : varying the size of objects or subjects, so that some are smaller than others and the illusion of depth is created.hope this : )