(1) Zinc - Essential for tissue repair
(2) Cobalt - Essential for formation of leucocytes
(3) Iodine - Synthesis of thyroid hormones
(4) Manganese - Synthesis of insulin
$\begin {array} {1 1} (1)\;B \: and \: C & \quad (2)\;A\: and \: D \\ (3)\;A \: and \: C & \quad (4)\;A\: and \: B \end {array}$
