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The bob of a pendulum of length l is pulled aside from its equilibrium position through an angle  and then released. The bob will then pass through its equilibrium position with a speed v, where v equals

(a) $\sqrt{2\mathrm{gl}\left(1-\mathrm{sin\theta }\right)}$

(b) $\sqrt{2\mathrm{gl}\left(1+\mathrm{cos\theta }\right)}$

(c) $\sqrt{2\mathrm{gl}\left(1-\mathrm{cos\theta }\right)}$

(d) $\sqrt{2\mathrm{gl}\left(1+\mathrm{sin\theta }\right)}$