Here's a problem to solve: Which of these is an example of water changing from water vapor to liquid?

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

- A: moisture forming on a mirror when you breathe on it
 
- B: sweat forming on your body when you exercise
 
- C: ice cubes melting when you put them in a warm liquid
 
- D: rivers drying up during a very hot summer
 