6) A randomized controlled trial is conducted to evaluate the incidence of diarrhea in 300 children with otitis media treated with a broad-spectrum antibiotic, amoxicillin + clavulanic acid, compared to amoxicillin. During the study, the participants and the investigator were not aware of the treatment allocation between experimental and control groups.

This study is:

1. Open-label
2. Single-blinded
3. Double-blinded
4. Non-blinded

The study design described above reduces:

1. Adverse drug reactions
2. Degree of bias
3. Compliance to the study protocol
4. Drop-out rate of participants
5. Duration of the study