Here's a problem to solve: Under which conditions would a sugar cube dissolve most quickly when placed in a liter of water at room temperature?

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

- A: A whole sugar cube is added and the water is stirred.
 
- B: A whole sugar cube is added and the water is not stirred.
 
- C: A crushed sugar cube is added and the water is stirred.
 
- D: A crushed sugar cube is added and the water is not stirred.
 