A Pendulum Bob Has Potential Energy U0 When Held Taut $\degree$

Multiple Choice

A pendulum bob has potential energy U0 when held taut in a horizontal position. The bob falls until it is 30 $\degree$ away from the horizontal position, when it has potential energy UA. It continues to fall until the string is vertical, when it has potential energy UB. Compare its potential energies at O, A, and B.

A) U0 = UA = UB.
B) UA- UB = 2U0.
C) UA - UB = U0 - UA.
D) U0 = UB = 2UA.
E) U0 - UA = 2(UA - UB) .