Select the most appropriate meaning of the given idiom.

Up in arms

Angry about something

The most appropriate meaning of the idiom "up in arms" is angry about something.

The other options are incorrect.

• "Divide into armed groups" is not the same as up in arms. Dividing into armed groups means to form a group of people who are armed and ready to fight.
• "Throw up arms in joy" is not the same as up in arms. Throwing up arms in joy means to raise your arms in the air in excitement or happiness.
• "Give up fighting and surrender" is not the same as up in arms. Giving up fighting and surrendering means to stop fighting and admit defeat.

The idiom "up in arms" comes from the idea of people being so angry that they are ready to fight. For example, if a group of people is up in arms about a new policy, it means that they are very angry about the policy and are willing to fight against it.