In which sentence is the word “double” used as an adjective?

(1 Point)

That number is expected to double over the next decade.

The actor had a stunt double for some of the scenes.

I thought I was seeing double when I was introduced to the twins.

That word has a double meaning.

That word has a double meaning.

The sentence in which the word "double" is used as an adjective is: "The actor had a stunt double for some of the scenes."