Sarah and evan are in the same science class. the teacher asks the class to design an experiment to determine the effect of acid rain on limestone. sarah designs an experiment which uses chalk and carbonic acid at a ph of 5.7, because she knows that chalk has the same chemical make-up as limestone and she knows that acid rain is primarily made up of carbonic acid at a ph around 5.7. evan designs an experiment which uses limestone tiles and acid rain collected from the environment. how do these experimental methods compare? a. sarah's experimental results will be easier to predict. evan's results will be impossible to predict since he uses real acid rain. b. sarah's materials are cheaper and easier to obtain, but evan's materials will allow him to better mimic real life. c. evan's experimental design will prevent him from being able to form a logical conclusion, whereas a conclusion can be made with sarah's design. d. evan's experiment can be preformed at any time, but sarah's experiment can only be performed when there is a rainstorm.