Which of the following describes a gradual increase in volume?

A gradual increase in volume is defined as a crescendo. This term originates from the Italian word "crescere," which means "to grow." In musical notation, a crescendo is indicated by a symbol that looks like a widening angle or sometimes the word "crescendo" itself, instructing the performer to progressively increase the loudness of the music over a specified passage.

This technique is crucial for creating dynamics within a piece, allowing for a build-up of intensity and emotion. It is often used to highlight climactic moments, adding depth to the performance. Understanding the concept of a crescendo enhances a musician's ability to express the various nuances of a piece, contributing to the overall interpretative qualities of the music.