Answer:
Your question is poorly written, but as far as what was read the best thing would be a longitudinal study since you could see the evolution over time of the twins.
Explanation:
Longitudinal studies, unlike cross-sectional studies, are studies that analyze a factor in a population over time, thus analyzing the possible variables that occurred in those years, months or days. In simple words, the evolution over time is what a longitudinal study is based on (On the other hand, not a transversal one, since it would investigate a specific problem at a specific moment in time)
Answer:
Cheer them up! Try not to bring why they are depressed into whatever you are doing. If they don't want to or just want to be alone, just let them. Everbody wants to be alone sometimes.
If there are no multiple choices then i just thonk he should quit
