A study was conducted to investigate the prevalence of smoking of family members and friends among adolescents. The study used the Global Youth Tobacco Survey (GYTS) questionnaire. The studied population consisted of 3000 high school students who were selected randomly. Data was collected from students anonymously, without supervision of school authorities.

Based on the above

(1) What is the study design used?

(2) Is the study observational or experimental?

(3) Is the study descriptive or analytic?

(4) Is the study prospective, retrospective, or cross-sectional?