Answer: Independent variable is model of SUVs
Explanation:
An experiment is performed based on the efficiency SUVs. In order to to check the efficiency of the different models of SUVs they kept the amount of fuel constant.
The independent variable in this experiment is different models of SUVs. As different SUVs will have different efficiency.
The controlled variable in the experiment is amount of fuel which is kept constant at 10 gallons of gasoline.
The dependent variable in the experiment is miles driven as it will depend on the model of SUVs because the controlled variable is kept constant.