A man moves 20 m North, then 10 m east and then $ 10\sqrt2$m south-west, his displacement is :

Question

$\begin {array} {1 1} (a)\;20\: m\: North & \quad (b)\;10\sqrt2m\: north-west \\ (c)\;10\sqrt2m\: south-east & \quad (d)\;10 \; m \: North \end {array}$