The reagent used in the Wolff - Kishner reduction is :

Question

$\begin {array} {1 1} (1)\;H_2N-NH_2\: / \: KOH & \quad (2)\;H_2\: /\: Ni \\ (3)\;Sn\: /\: HCI & \quad (4)\;LiAIH_4 \end {array}$