Asked by pls check

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