Answer:
The domino theory or also called snowball effect sequence, arose during the cold war, and is applied to international politics according to which, if a country enters a certain political system, it would drag others from its area towards that same ideology.
A clear example was the communist ideology that the Soviet Union proposed by annexing countries that had been part of the Russian Empire such as Ukraine, Belarus or the Baltic Republics during World War II towards the same ideology.
Taking this definition into account we can discard Options B and D. That leaves us with Option A. neighbors will become democratic. if one country becomes democratic, but because the Domino Theory as such was implemented for communists countries during the Cold War then the correct answer is <u>Option C</u>
Answer: the number of residents has grown substantially
Explanation: