Books that are surrounded by oxygen will turn yellow, so basically, all books since oxygen is constantly surrounding us. Oxygen-rich conditions are very bad for paper, which gives them the yellow tiny. This is actually called lignin oxidation! Lignin oxidation gives it a yellow or brown colour as you said. Yellow comes first, then brown after.
I hope this helped a bit! :)
It’s the first statement “as many as 58 percent pet owners claimed that caring for their pets taught children responsibility”
The answer would be vault : crash down : start : stop
The first two are opposites, so start : stop would complete the analogy
