A diagram shows a glass flask containing water at $10^\text{C}$. A long glass tube runs through the bung and down into the water. The water level in the tube is at $X$. The flask is then put into hot water, and the water level in the tube eventually rises to $Y$. What causes the water level to rise?
- AThe flask contracts and the water expands.
- BThe flask contracts more than the water contracts.
- CThe flask expands and the water contracts.
- DThe flask expands less than the water expands.