The image below is the question

-- If A burns out, then all six bulbs go out, and an inky blackness descends over the whole circuit. (Choice-A).  The battery is happy though, because it doesn't have to supply ANY energy.

-- If D or E burns out, then all five of the not-burned-out bulbs still shine.

-- If F or C burns out, then A, B, D, and E still shine.

-- If B burns out, then A and D still shine.

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this