The diagram shows air enclosed in a flask by a small amount of water in a narrow tube. When a student holds the flask in their hands, the small amount of water first moves downward from P to Q, and then upward to R. Why does the small amount of water move in this way?
- AThe flask contracts and then the air expands.
- BThe flask expands and then the air contracts.
- CThe flask expands and then the air expands less than the flask.
- DThe flask expands and then the air expands more than the flask.