Unitary system of government is adopted by some states because
The correct answer is: A
Explanation
A unitary system of government is often adopted by states that are homogeneous. In a unitary system, the central government holds most of the power, and this system works best in nations where the population has a lot in common, such as shared culture, language, and values. The other options do not directly relate to the reasons for adopting a unitary system.