Which statement accurately describes a cause-and-effect relationship described in this excerpt?

Because Napoleon departs for France, the French army and scholars decide to stay in Egypt.
Because the French army and scholars decide to stay in Egypt, Napoleon decides to depart for France.
Because the French soldiers are tearing down a ruined wall in a fort, they discover the Rosetta Stone.
Because the French soldiers are searching for the Rosetta Stone, they tear down a ruined wall in a fort.