Final answer:
In musical composition, Repetition, Contrast, Unity, and to some extent, Texture interact to create a sense of shape and structure, with each element contributing to the cohesiveness and dynamic quality of the piece.
Step-by-step explanation:
The elements that interact in a musical composition to produce a sense of shape and structure are Repetition, Contrast, and Unity. Texture is also an element that can influence the perception and depth of a composition, although it is often discussed in the context of the material attributes in visual arts. In music, it could refer to the layering of sounds and how they interact. Repetition creates rhythm and helps to establish a recognizable pattern which provides cohesion to a piece. Contrast offers variety and engages the listener through dynamic changes and differing elements. Unity is the overarching sense of cohesiveness that makes a musical composition feel complete and satisfying. All these elements work in tandem to give a musical composition its unique character and form.