A scientist wants to determine if a new fertilizer increases plant height. She grows two groups of identical plants: one group receives the new fertilizer, and the other receives no fertilizer. What is the independent variable in this experiment?
✓ Correct Answer: Option C
The independent variable is the factor that is intentionally changed or manipulated by the experimenter. In this case, the scientist changes the fertilizer type (or presence/absence of fertilizer) to observe its effect.