Answer:
Increase
Step-by-step explanation:
According to the research conducted by A.F Williams and K.A Lancaster, in 1995, in their book or research work titled "The prospects of daytime running lights for reducing vehicle crashes in the United States." It was concluded amongst other things, that Daytime running lights INCREASE visual contrast between vehicles and their background, improving their noticeability and detectability.
Hence, the right answer is INCREASE.