Question

Which type of study contains a treatment?

Sample.
Experiment.
Survey.
Observational study.

Answer 1

The type of study that contains a treatment is called EXPERIMENTAL STUDY.
An experimental set up usually involved random assignment of variables into different group and manipulation of a particular variable while others are controlled. This type of study is usually done to determine the effect of one variable on the outcome of another variable. The experimental set up is usually made up of control and treatment groups.

Answer 2

Typically, in an experiment there are two groups. One group is called the control group. The other group is the experimental group. This second group receives some sort of treatment. The control group does not. The idea is to see if the treatment has an effect on those who receive it by comparing them to a comparable group that does not receive the treatment.

So the answer is experiment.