What is the primary function of daytime running lights or dipped low-beam headlights when driving in dense fog, dust storms, or heavy tropical rain?

1. To improve vehicle visibility to other road users without creating blinding glare reflections
2. To illuminate the road up to 500 metres ahead using high-power beams
3. To signal to police that the vehicle's electrical alternator is operational
4. To warm up the windshield wiper motor during rain