A researcher has conducted an experiment in which she has given participants a placebo, 10mg, and 20mg of a drug. She then measured their anxiety, blood pressure, and heart rate in response to the drug. How many levels does this experiment’s independent variable have? (Points : 1)

Question

A researcher has conducted an experiment in which she has given participants a placebo, 10mg, and 20mg of a drug. She then measured their anxiety, blood pressure, and heart rate in response to the drug.  How many levels does this experiment’s independent variable have? (Points : 1)
       Two
       Three

Four
       Five
my answer is two

Janice · Answer

TWO is the wrong answer..I just got it wrong on the quiz. The correct answer is THREE.