Final answer:
The correct response when facing high-beam headlights from an oncoming vehicle at night is to look at the white line on the right side of the road to avoid being blinded and maintain safe driving.
Step-by-step explanation:
When an oncoming vehicle has its high-beam headlights on at night, the correct action to take is to look at the white line on the right side of the road, which corresponds to option C. This technique helps to avoid being blinded by the high beams while still being able to see enough of the road to continue driving safely. It is not advisable to turn your high beams on or flash your high beams, as this can exacerbate the issue and potentially cause a hazardous situation for both drivers.