It's a common belief that people behave strangely when there's a full moon and that as a result police and emergency rooms are busier than usual. If you wanted to find out whether there is any value...

My question is attached to this.

Extracted text: It's a common belief that people behave strangely when there's a full moon and that as a result police and emergency rooms are busier than usual. If you wanted to find out whether there is any value to this belief, what kind of study would you use and why? A. experiment; use as a control, those days when there is no full moon B. experiment; use blinding and don't tell anyone what you are looking for C. prospective observational study; find out which days are full moon days and talk with officers and emergency room personnel D. retrospective observational study; it is easier to go back three years to find data to support the belief