Final answer:
The process of passing from one key to another in music is called modulation, which adds narrative depth or emotional intensity. Other terms such as transposition and development have different meanings in the context of music.
Step-by-step explanation:
The process of passing from one key to another in music is called modulation. This term refers to the change of key within a piece. Modulation usually occurs to introduce a new level of narrative depth or emotional intensity to the music. In contrast, the term transposition refers to playing a piece of music in a different key than originally written, whereas development is a term often used in sonata form to describe the evolution and alteration of themes. The term transformation may refer to various changes but is not typically used to describe changing key in music.