Select the most appropriate meaning of the underlined idiom in the given sentence.

The wedding preparations are in full swing.

at the height of activity

The most appropriate meaning of the underlined idiom in the given sentence is at the height of activity. The idiom "in full swing" means that something is happening very actively or vigorously.

The other options are not as appropriate.

• Hard to arrange means that something is difficult to organize or put together.
• In great difficulty means that something is happening with a lot of problems or challenges.
• Very costly affair means that something is very expensive.