If x, y, z are in A.P. and $\tan^{-1}x,\tan^{-1}y$ and $\tan^{-1}z$ are also in A.P then :

Question

$\begin{array}{1 1} (1) x=y=z \\ (2) 2x=3y=6z \\ (3) 6x=3y=2z \\ (4) 6x=4y=3z \end {array}$