Pablo and Johanna must complete a yearlong study for their biology course. After some discussion, they decide to compare dog diets. To test their hypothesis that the local veterinarian's special dog food mix will enhance growth and development, each student adopts a puppy from the local pound. Pablo plans to feed his goldendoodle the special diet, while Johanna plans to use generic dry kibble from the supermarket for her bulldog. Pablo and Johanna have too many ________.

A dependent variable is a variable that the experiment seeks to observe and measure, this variable is expected to change in value throughout the experiment and depends on other variables. An independent variable is one that the researcher changes throughout the experiment in order to see what effect it will have on the dependent variable. Finally, the control variable is the variable that remains the same throughout the experiment in order to limit the influence they will have on the outcome. If the value we wish to measure changes, the presence of control variables helps to narrow down and correctly credit the cause of this change, leading to a valid experiment.

In the situation given, Pablo and Johanna have too many independent variables. The dependent variables that Pablo and Johanna wish to measure are dog growth and development. The independent variable is the one they change in order to see what effect it will have on the dependent variable, in this case, the dog food. However, the experiment would not be valid because the breed of dog should be a control variable to ensure correct data, given that different breeds of dogs grow and develop at varying rates. This variable is instead an independent variable in this given experiment, given that it changes between the two groups and will affect the outcome.

For more on experiments and variables see:

https://brainly.com/question/24372733