Net magnetic field at the centre of the circle $O$ due to a current carrying loop as shown in the figure for $\theta < 180^{\circ}$ is

Question

$\begin {array} {1 1} (a)\;Zero \\ (b)\;Perpendicular\: to\: the\: paper\: inwards \\ (c)\;Perpendicular \: to \: the\: paper\: outwards \\ (d)\;Is \: perpendicular\: inwards\: or\: outwards\: depending\: on\: the\: value \: of \: theta \end {array}$