Identify the Type of Observational Study (Cross-Sectional, Retrospective, Prospective)

Identify the type of observational study (cross-sectional, retrospective, prospective).
-In a clinical trial for a new headache medication, participants are randomly assigned to a treatment group or a
placebo group. They do not know whether they are receiving the medication or a placebo. However the doctors
administering the medication and evaluating the results do know which participants are receiving the
medication. This experiment is blind but not double blind. Explain what this means and why the absence of
double blinding could cause a problem.