The answer is c, kia1800 is correct because like that person said it's a graphical model that displays one or more weather elements. A hypothesis is a prediction made, based on observations, about the results of a scientific story or experiment so that's not the answer. A scientific theory try to explain an observation by experimentation and observations so that isn't the answer either. Also a variable are the things in a experiment that changes so that also isn't the answer.
The swimming pools pH is below 7, meaning it is slightly acidic. If you want to make the pH higher, you must add a base which by definition has a pH higher than 7.
