Which occurs as a result of Earth's tilt on its rotating axis? OPTIONS:
- movement of the tides
- prevalent or trade winds
- seasonal changes in the climate
- light and dark changes of day and night
A: seasonal changes in the climate

Scientists dig in a dry area at the bottom of a mountain range. Fossilized shells of freshwater mussels are found in the area. Which is a likely conclusion that scientists will draw based on this evidence? OPTIONS:
- Rivers once flowed through the area.
- Volcanoes were once active in the area.
- The ocean shoreline once reached this area.
- Floods were a common occurrence in this area.
A: Rivers once flowed through the area.

Radio signal interruption sometimes causes a humming or buzzing sound. These sounds are most likely caused by OPTIONS:
- balanced forces.
- longitudinal waves.
- gravitational forces.
- electromagnetic waves.
A: electromagnetic waves.

The prairie grass ecosystem once had a deep layer of topsoil which was protected by the grasses that covered it. Removal of these grasses for farmland is causing the soil to be eroded mainly by OPTIONS:
- wind and rain.
- animal movement.
- crops grown in the soil.
- increased temperatures.
A:
wind and rain.