Answer:
The correct answer is : b. the 30 arms with the new formula
Explanation:
Independent variable is a variable that is present in the experiment and research experimenting about and do not depend on any other variable. In this experiment the researcher is experimenting about the new sunscreen and its effect on the people.
In this experiment the 30 arms with new formula is independent variable that would change or altered the dependent variable.
Thus, the correct answer is : b. the 30 arms with the new formula