Which controlling idea would go with an essay that has the following hook: Did you know that doing things you have never done, whether it is trying a new food or bungee jumping, is good for your brain and body?Exercising is the most important thing you can do to stay healthy and strong. People who try new things are healthier and more creative than those who do not. Doing something that you find difficult is one way to learn and grow personally. People who eat healthy foods are more likely to learn better and be stronger.

Sally and sue were investigating the topic of friction in science. they used a small car and a ramp as seen in the picture to test what they were learning. they knew that they slipped easily on waxed floors but not on carpet, so they decided to change the material on the surface of the ramp to see what happened. they planned to use glass, carpet, aluminum foil, and sandpaper and run the car down the ramp over each surface. what would be the best research question to guide the girls' experiment? a) does the amount of surface area affect the friction on the moving car? b) will the car travel fastest on the glass surface? c) how does the angle of the ramp affect the speed of the car? d)do rougher surfaces tend to create more friction than smooth surfaces?