Problem: Except for their color, there are two identical inflatable chairs in a grade school classroom that the children can use during free time. Today, Patrick and Mark, who weighs much more than Patrick, are allowed to use the chairs. Patrick chooses to sit on the red chair, and Mark sits on the green chair. The boys have fun reading books while they sit on their comfortable inflatable chairs. Which chair has a higher air pressure?

A: green chair

Problem: Kelsey is bored in class, and sees a coil of wire with electricity running through it. There is a box of random pieces of iron on the teacher's desk so she goes and picks up two of them. Piece A she simply puts on her desk to use later, and Piece B she slowly passes through the coil of wire. Which piece of iron is more magnetized?

A: Piece B

Problem: Two sister cities were both situated on plate boundaries, close to volcanoes, on different continents. Red city was 10 miles from a volcano, while Tree city was 60 miles away. Red city experienced many earthquakes, Tree city few and far between. Which city experienced fewer rocks breaking?

A: Tree

Problem: John is a nuclear scientist who works at the Fermi lab. Today, in front of him he has four samples, sample A, sample B, sample C, and sample D. Sample A is the naturally occurring uranium. Sample B is enriched uranium. Sample C is the U-238, and sample D is the U-235. He needs to figure out how to best use them. Would sample A have higher or lower percentage of uranium-235 than sample B?

A:
lower