Musicologists have been studying the work song, a piece of music closely related to a specific type of work. Some specific categories of American work songs include cowboy songs, agricultural work songs, and sea shanties sung by sailors. These songs were sung without the use of instruments, and in some work situations they helped to establish rhythm among the workers. For example, sailors sang work songs when engaging in activities that required coordinated efforts such as rowing, raising the anchor, or adjusting the rigging. If the underlined phrase were deleted, the sentence would primarily lose a detail that . is grammatically incorrect provides relevant and specific examples is redundant and unnecessary is irrelevant to the main idea