Which excerpt from the passage provides evidence of a problem-and-solution structure?

“A rock drawing in Spain . . . shows a man . . . holding a hive.”
“A lucky wanderer . . . could stumble on a hive.”
“People in the Americas had no bees.”
“You could hollow out a log near bees, and they would make it their home.”

“You could hollow out a log near bees, and they would make it their home.”