Which is a complex sentence?

 - Freedom of speech and trial by jury are two important rights in the United States Constitution.
 - Kyle picked raspberries in the field until his fingertips were stained red.
The second sentence is the complex sentence. It is made up of an independent clause and a dependent clause. The dependent clause begins with the subordinating conjunction until.
Kyle picked raspberries in the field until his fingertips were stained red.