Which is a complex sentence?

 - According to many scholars, the 1798 publication of Lyrical Ballads by Samuel Taylor Coleridge and William Wordsworth began the romantic period in English literature.
 - Celine and her mom sat on the back porch and watched as the sun sank into the horizon.
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 as.
Celine and her mom sat on the back porch and watched as the sun sank into the horizon.