3. Chopin's Nocturne in E Flat Major from this unit and his Prelude in E Minor from Part I (Elements) exhibit the technique of , a "slight holding back or pressing forward of tempo" in which one note is given more time than the notated rhythm calls for and the next note is given less.

Rubato is the answer.

Explanation:

Rubato means slightly holding back or pressing forward of tempo.

option c (nickel) is not found in earth's crust. the earth's crust basically contains eight (8) elements namely: oxygen, silicon, aluminum, iron, calcium, sodium, potassium and magnesium (listed in order of abundance).