What are you demonstrating when you squeeze the bottle?

Imagine you are demonstrating how parts of the circulatory system work. You squeeze a plastic bottle filled with red-colored water. The force of the squeeze pushes the water into a tube attached to the top of the bottle.
A.
The pumping motion of the heart
B.
The flow of blood through the arteries and veins
C.
The flow of gases into and out of tissues
D.
The gas exchange that takes place in the lungs
What are you demonstrating when you squeeze the bottle?