Select the most appropriate meaning of the given idiom.

Through thick and thin

Under all conditions

The most appropriate meaning of the idiom "through thick and thin" is under all conditions. It is an informal expression that means to support or stay with someone or something, even when there are problems or difficulties. The idiom is thought to have originated in the 16th century, and it is believed to be a reference to the fact that a thicket is a dense area of trees or bushes, which can be difficult to navigate.

The other options for the meaning of the idiom are incorrect. Humility is not the same as staying with someone through thick and thin. Ego and pride are not the same as staying with someone through thick and thin. Staying with someone with all kinds of people is not the same as staying with someone through thick and thin.