Fanny Mendelssohn Hensel's September: At the River is a character piece, which is a short piano work with a descriptive title that evokes a particular mood, scene, or person. What is the instrumentation of Hensel's work?

One Piano

Explanation:

The instrumentation of the "At the river" character piece is one piano.

The movement of the notes conveys the movement of a flowing river

In character piece, piano are relatively used for brief musical composition to express mood and idea and they are always used to channel a single mood or impression