Answer:
Vitamin C is the independent variable and problem solving performance is the dependent variable.
Step-by-step explanation:
The independent variable is the variable that can be manipulated or changed to measure its effect. Vitamin C dosage can be changed for difference individuals to see the effect on their problem solving performance.
Dependent variable is the variable on which the effect of independent variable is measure i.e the effect of vitamins C with different dosage will be known or measured base on problem solving performance of an individual.
Therefore ability to solve problems by individual after the intake of vitamin C means its depends on Vitamin C intake.