Here's a problem to solve: A student poured water into a plastic tray. The student then put the tray into the freezer. What property of the water changed as the water froze?

Among the 4 following options, which is the correct answer?

- A: The water became a gas.
 
- B: The mass of water increased.
 
- C: The water took a definite shape.
 
- D: The flavor of the water changed.
 