According to the principles of relativity, the speed of light in a vacuum is always measured to be \(300,000\) km/s, regardless of the motion of the source or the observer.
So, for the person measuring the light coming from the car's headlights, the speed they would measure for light is:
300,000 km/s.
The other options would incorrectly imply that speeds can add in a classical sense, which is not how light behaves in relativity.
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