Aluminium reacts with $NaOH$ and forms compound 'X'.If the coordination number of aluminium in $'X'$ is 6, the correct formula of X:

Question

\[\begin {array} {1 1} (1)\;[Al(H_2O)_4(OH)_2]^+ & \quad (2)\;[Al(H_2O)_3(OH)_3] \\ (3)\;[Al(H_2O)_2 (OH)_4]^{-} & \quad (4)\;[Al(H_20)-6](OH)_3 \end {array}\]