Which is a complex sentence?

 - Before Melissa's birthday party, Franklin wrapped her present with delicate silver tissue paper.
 - Johnny 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.
Johnny picked raspberries in the field until his fingertips were stained red.