What distinguishes a symphony from a concerto?

A symphony is distinguished from a concerto primarily by its structure, which typically consists of four movements. This format, often following a fast-slow- scherzo/third movement-fast sequence, provides a contrasting framework that allows for a wide exploration of themes, textures, and dynamics throughout the work.

In contrast, a concerto is generally structured around a dialogue between a solo instrument and an orchestra, usually consisting of three movements. This format emphasizes the virtuosic abilities of the soloist, showcasing their technical skill and expressiveness.

The other choices either misrepresent the characteristics of these forms or do not correctly address the key differences. For instance, a symphony is not a solo work; it is composed for an orchestra. Additionally, a symphony typically has multiple movements rather than just one, and it can feature a variety of instrumental combinations, not limited to string instruments as suggested in the last option. Thus, the defining attribute of a symphony being in four movements serves to highlight its more complex and integrated musical structure compared to a concerto.