The bob of a pendulum of length l is pulled aside from its equilibrium position through an angle `theta` and then released. The bob will then pass through its equilibrium position with a speed v, where v equals
A. `sqrt(2gl(1-sin theta))`
B. `sqrt(2gl(1+cos theta))`
C. `sqrt(2gl(1-cos theta))`
D. `sqrt(2gl(1+sin theta))`
