Problem: - A muscle fiber gets a signal from its nerve - Proteins and chemicals release energy to either contract the muscle or relax it - When the muscles contracts the bones connected to he muscle are pulled closer together - When the muscle relaxes the bones move farther apart. What might be the first step of the process?

A: Muscles work by expanding and contracting

Problem: - Diaphragm and other muscles expand to allow room for your lungs to fill - The air flows into the narrow bronchioles in the lungs - From the bronchioles to the alveoli - The oxygen enters into the bloodstream - Is switched with the carbon dioxide in the bloodstream - The carbon dioxide enters through the alveoli - Through the narrow bronchioles - Into the lungs - The carbon dioxide is exhaled out of the body. What might be the first step of the process?

A: You breathe in

Problem: - The magma goes into volcanos - The volcanos pressure the magma upwards - The pressure causes the magma to push through the surface of the volcano - The lava cools - The lava forms new rock - New magma is pressured to the surface of the volcano - The volcano bursts through the rock the formed after the last eruption. What might be the first step of the process?

A: Magma rises from deep in the earth

Problem: - The sediment rolls down hill towards a river - The heavy items sink to the bottom - The lighter items float on the top and in convection cycles - As the river flows the sediment is moved - The sediment gets dumped through tributaries into lakes and the ocean - The sediment keeps moving around the world in convection currents. What might be the first step of the process?

A:
Sediment becomes loose from the rest of the soil