An ecologist conducts a greenhouse experiment to study the effect of water concentration added to soil on the productivity of sunflower seedlings. what is the independent variable in this experiment?

Aresearcher created three groups based on participants bmi: normal weight, overweight and obese. the hypothesis being tested is that the three groups differ in the mean number of artificially sweetened drinks consumed weekly. which statistical test might the researcher use, assuming a reasonably normal distribution of values.