Which muscle runs down the front of the abdomen and is used when doing crunches (also known as the six-pack abs)?
a. rectus femoris
b. quadraceps femoris
c. rectus abdominis
d. gluteus maximus

Which is one way that sinkholes can form? a) tornadoes touch down and destroy trees and brush b) rivera overflow during a storm and wash away nearby land c) rainwater flows away from a depression in the ground d) groundwater dissolves the limestone and other rocks in the ground