A study is planned to compare two oral health programs in reducing tooth decay for adolescents aged 12 -17. The first program is based on oral health education and the second is based on access to preventative dental care services. The study will involve 600 participants and each participant will follow each program. The programs will be assigned in random order (i.e., some participants will first receive oral health education and then have access to preventative dental care services, while others will first have access to preventative dental care services and then receive oral health education). The degree of tooth decay will be compared between treatments. Identify the type of study design proposed:

A. Randomized cross-over

B. None of the provided

C. Case-control

D. Cross-sectional

E. Cohort