A. size
B. defence
C. population
D. homogeneity
Correct Answer: Option D
D. homogeneity
Explanation
Different groups within a country may adopt federalism as a means of preventing the over-concentration of power at the centre. This is one way in which they can prevent the country from drifting into dictatorship. States with a common historical background can come together to form a federation.
Homogeneity is the quality or state of being all the same or all of the same kind.