A sample with $x$ mol of $\text{Al}_2\text{Cl}_6$ is mixed with water to form solution W. To precipitate all the aluminium as its hydroxide, $y$ mol of sodium hydroxide are needed. Further alkali is then introduced to dissolve the precipitate again, producing solution Z. Which of the following statements are correct?
- A1, 2 and 3
- B1 and 2 only
- C2 and 3 only
- D1 only