Question

research question: \does the type of gasoline put in a car affect how fast the car can run?\ in this experiment, what is the independent variable?
amount of gas is put into the car
how fast the car can run
type of car the gas is put into
type of gasoline

Explanation:

The independent variable in an experiment is the factor that is manipulated or changed to observe its effect on the dependent variable. The research question is about how the type of gasoline affects the car's speed. So the independent variable should be the type of gasoline, as it's the factor being varied to see its impact on the car's speed (the dependent variable).

Answer:

type of gasoline