Final answer:
The correct method to eliminate or reduce arc blow while welding is to decrease the welding current. Increasing current or voltage may worsen arc blow by strengthening the magnetic field's influence.
Step-by-step explanation:
To select the method to eliminate or reduce arc blow, consider the effects of welding current and external magnetic fields on the arc. Arc blow is the deflection of the welding arc from its intended path, commonly caused by magnetic fields surrounding the weld. The correct method to reduce or eliminate arc blow is not to increase the welding current or use a higher voltage; both options can actually worsen the situation by increasing the magnetic field's influence on the arc.
Instead, one effective method is to decrease the welding current, which can reduce the strength of the magnetic fields produced by the current itself. Using direct or alternating current with proper technique also helps in managing arc blow. External magnetic fields should be avoided or cancelled out through appropriate setup, which sometimes includes the use of demagnetization coils, not by adding more magnetic fields as suggested in option 3. Therefore, the correct option is to decrease the welding current.