Select the most appropriate study design to explore each of the public health issues outlined below.
1.The association between depression and binge eating in obese adolescents and adults.
2. The long term effects of detention on the mental and physical health of asylum seekers.
3. Folate supplementation during pregnancy and development of autism in offspring.
4. Testing a drug for use in elderly people diagnosed with Alzheimerâ€™s Disease
. . .