D) The tray would need to be raised higher before the items start to slide.
Explanation:
The tray would need to be raised higher due to the gritty sandpaper causing it to have more grip or fraction between the two surfaces. In the first experiment it would have a smooth surface to slide across but in the second experiment it would have a rougher surface to slide across.
Example: It would be like taking two different kinds of shoes like tennis shoes and football cleets. Then seeing which one has more traction when going up a hill.
Because the temperature and the radiation are not correlated, they're not represented as functions of each other, they're represented as independent variables thus using graph 5 you cannot figure out how one affect another
