A farmer divided his piece of land into4 equivalent groups. The quality of the soil is the same across the4 groups of land. He planted the same crop in all4 groups of landand recorded the yield of the crop in all4 groups for a4 week period. Is the study observational or experimental? If it is an experiment, what is the controlled factor?

Select the correct answer below:

1) The study is an observational study.

2)The study is an experiment. The controlled factor is the4 week observation period.

3)The study is an experiment. The controlled factor is the land.

4)The study is an experiment. The controlled factor is the growth of the crops.