Before welding a cracked section of a motorcycle frame, why must the technician disconnect the battery and remove nearby flammable components such as fuel lines?

1. To prevent electrical damage from welding current and to reduce the fire or explosion risk from fuel vapours near the weld
2. Because welding requires the motorcycle's battery to power the welding machine directly
3. Because fuel lines improve the strength of a weld joint
4. Because disconnecting the battery increases the frame's rigidity