Which is an example of restricted free speech?

promoting an idea that is unpopular with most people

telling everyone you lost your job when you are still employed

revealing a confidential e-mail that was sent to you by mistake

writing an article that urges people to violently protest unfair treatment

Writing an article that urges people to violently protest unfair treatment.

The Supreme Court has declared that advocating the use of force is not protected as free speech, when it is likely to incite such an action. This article would fall under that category and therefore it is restricted free speech.