Which sentence is an example of a simple sentence pattern?

1.After John heard the news, he left.
2.John left the room.
3.John left the room, and the room seemed empty.

sentence #2

Explanation:

A VERY SIMPLE explanation

A simple sentence is an independent clause that expresses a complete thought.

Sentence #1 is a complex sentence; it is made up of a dependent clause and an independent clause.

Sentence #3 is a compound sentence; it has two simple sentences (independent clauses) connected together.

I could elaborate with much more information, but that might be too much information for this simple - no pun intended - question.  

dont know what all this is english this is america.