What does the author convey in the passage

You need to add the passage 

One question  you could  ask  is why are lights on police cars red and blue? you can begin to answer this question by saying, the original color was red but it was harder to see so they used red and blue together to create more visible lights. you can ask another question about red  ink and talk about pros and cons of using them to grade papers. you can then put where you got your information and turn in your assignment!