4. Recall that an observational study can be used to prove a correlation. Think of an observational study that you have learned about, or make up your own example.
a. Give a sample question or hypothesis for this observational study

How are extrusive rocks formed? magma gets trapped inside earth and cools to rock. volcanoes apply force to solid rocks and eject them. magma gets forced to earth’s surface and cools to rock. volcanoes trap lava inside earth, where it cools to rock.

Why do leaves change color in the fall? green pigments break down and no longer mask the color of chlorophyll. chlorophyll breaks down and no longer masks the colors of other pigments. red- and yellow-colored pigments grow and mask green-colored chlorophyll. green-colored chlorophyll breaks down and turns red and yellow.

The polio virus can cause skeletal muscle paralysis by destroying neuron cell bodies. what area of the spinal cord is destroyed