Select the most appropriate meaning of the given idiom.

Bread and butter

Livelihood

The most appropriate meaning of the idiom "bread and butter" is livelihood. This idiom refers to the main source of income for a person or organization. The image of bread and butter is one of basic sustenance, and so the idiom is used to describe something that is essential for survival.

The other options for the meaning of the idiom are not accurate. To be major means to be of great importance or significance. To reach a crisis means to come to a point of great difficulty or danger. To be ruined means to be brought to financial or moral ruin.