If you observe a weak, thin yellow spark at the spark plug electrode during a spark test, what does this indicate about the ignition system?

1. The ignition system is weak, possibly due to a failing ignition coil, a degraded spark plug cap resistor, or a weak stator exciter coil.
2. The ignition system is operating perfectly, as yellow is the correct spark color.
3. The engine air-fuel mixture is running extremely rich, staining the spark.
4. The battery is overcharging, forcing too much current through the ignition coil.