Please help, I'll be giving brainliest. Prove that the rational numbers are closed under addition. Please let me know if I'm correct, and if not what the answer should be, I'll be giving brainliest.

Consider the functions below. function 1 function 2 function 3 select the statement which is true about the functions over the interval [1, 2] a b function 3 has the highest average rate of change function 2 and function 3 have the same average rate of change. function and function 3 have the same average rate of change function 2 has the lowest average rate of change d.