Which of the following is an important advantage of experiments over observational studies?

Which of the following is an important advantage of experiments over observational studies? Check all that apply.

1. 1- Ensuring that each subject in the trial receives the best possible treatment
2. 2- Isolating the effects of a specific treatment
3. 3- Guaranteeing that approximately the same number of subjects is assigned to each treatment group
4. 4-Controlling for lurking variables to have a stronger case for causation