Answer
1) B
2) E
3) C
4) A or D
5) B or E
Work Step by Step
1) The force is the greatest at the steepest point in the curve, which is B.
2) If it has energy $E_1$, the electron cannot pass point E, for it cannot go above the horizontal line through $E_1$
3) If it has energy $E_2$, the electron cannot pass point C, for it cannot go above the horizontal line through $E_2$
4) Force is 0 where the slope is horizontal, which occurs at points A and D.
5) Points B and E are the points where the slope is positive, meaning that the the force is pointing left.
