It was broad daylight. All the passing cars had their headlights on due to the thick fog. (compound sentence)

It was broad daylight. All the passing cars had their headlights on due to the thick fog. (compound sentence)

It was broad daylight, but all the passing cars had their headlights on due to the thick fog./Though/Although it was broad daylight, all the passing cars had their headlights on due to the thick fog.