What occurs when the breaker points pull apart?

When the breaker points pull apart, they open the electrical circuit that supplies current to the ignition coil. This interruption in the circuit leads to a sudden drop in current through the coil, which generates a high voltage in the secondary winding. This high voltage is what causes the spark plug to fire, igniting the air-fuel mixture in the engine's combustion chamber. This process is essential for engine operation, particularly in gasoline engines that rely on this type of ignition system.

When considering the other choices, the idling of the engine is not directly related to the action of the breaker points; rather, it reflects the overall tuning and workload of the engine. While the circuit must open to produce a spark, the concept of battery charging and an ignition system reset are not relevant to the function of breaker points during their operation. The primary action when the points separate is to create a spark for ignition, firmly establishing the correctness of the selected answer.