Distance of the point $(\alpha, \beta, \gamma)$ from $y$-axis is

$\sqrt{\alpha^2 + \gamma^2}$

The correct answer is Option (3) → $\sqrt{\alpha^2 + \gamma^2}$ ##

$∴$ The given point is $(\alpha, \beta, \gamma)$

Any point of $y$-axis $= (0, \beta, 0)$

Required distance $= \sqrt{(\alpha - 0)^2 + (\beta - \beta)^2 + (\gamma - 0)^2} = \sqrt{\alpha^2 + \gamma^2}$