A mass $\mathrm{m}$ resting on a smooth horizontal slot is connected to another equal mass over a smooth pulley. The system is at rest when $\theta=\theta_{0}\left(\Delta \mathrm{y}<<\ell=\ell^{\prime}+\Delta \mathrm{y}\right)$. The velocity of the mass on the floor at $\theta=90^{\circ}$ is
(a) $\sqrt{2 \mathrm{gh}}$
(b) $\sqrt{2 \operatorname{gh}\left(1-\cos \theta_{0}\right)}$
(c) $\sqrt{2 \operatorname{gh}\left(1-\sin \theta_{0}\right)}$
(d) $\sqrt{2 \mathrm{gh}\left(\operatorname{cosec} \theta_{0}-1\right)}$