Karlie read this excerpt from "Mad Cow, Furious Farmer."

Look around your house. Think about everything held up by the walls and floors. What if, say, just one corner of your house suddenly got squishy? What if the corner wiggled with the wind? Nearby walls and pipes and roofing would bend with it. If that corner was not fixed, it could eventually ruin your entire house!

That is a little like mad cow disease, a brain disease caused by a speck of material that eventually ruins the entire brain. The speck of material is called a "prion" and it is dangerous.

Karlie predicts that the main subject of this excerpt is about

how mad cow disease starts in the brain and can affect humans.
how scientists study the brain and detect anger and madness.
how prions can cause a barn to become unstable and dangerous.
how farmers should protect barns and houses from cows and other livestock.