In an observational study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions.
In various fields an observational study draws deductions from a specimen to a populace where the independent variable isn't under the control of the scientist due to moral concerns or strategic requirements.
C. Al-Qaeda is not a branch of Islam.
Answer:
Explanation:
The rivers in Southwest Asia and north are important because without it people would have a harder time travaling to certain areas because there would be fewer landmarks. Also a lot of aqutic animals such as some fish and others.