A teacher wants to know if burning a scented candle affects students performance on pop quizzes. in the experiment there will be a treatment group and a control group each taking their quizzes in a room that either does or does not have a scented candle burning. why is randomization important when setting up an experiment to answer this research question?

to ensure that both groups have a nice mix of students

to ensure that the two groups have the same number of students

to ensure that both groups are roughly equivalent regarding students preparedness, anxiety levels and study skills

to ensure that the rooms for both groups are approximately the same regarding time of day temperature sound control and lighting.