In this task, you are given a question and answer for that. The answer will fill in the blank or will complete the unfinished question. Your task is to provide an explanation based on the given question or fill-in-the-blank statement, and answer.

[Q]: Question: Rachel was looking into the night sky. The darkest star is most likely: 
 Answer: the coldest
[A]: The hotter a main sequence star is, the brighter it is.


[Q]: Question: Two cars are going down the road, one weighs a ton, the other weighs two tons. If both crash, the car weighing two tons will have a momentum that is 
 Answer: larger
[A]: The more mass a moving object has or the faster its moving, the greater its momentum.


[Q]: Question: Mona lives in a city that uses much oil. If the mayor of that city decides to change their policy and the city begins using less oil, what happens to the amount of pollution generated by the city? 
 Answer: decreases
[A]:
Greater use of oil and other fossil fuels causes more pollution.