The circuit shown in the picture can be broken in four places. Which places can the circuit be broken and still have at least one light stay lit? How do you know?

Answer:
C & D
Explanation:
The C & D circuit places can be opened, in this way the bulbs in 1 & 2 will work. Since they would be connected in parallel with the battery.
The bulbs each have their respective resistance for this reason when they are connected to the battery a current is generated that flows through each of the bulbs.