The correct answer is - C. 1975 - 1999.
The period between 1975 and 1999 was a period in which the world population grew for around 2 billion people. Even thought that is the same rise as in the period between 1930 and 1975, still this period is shorter, and is just 24 years the world population grew from approximately 4 billion people to approximately 6 billion people.
An elected monarchy is a country where people choose their monarchs. In regular monarchies, inheriting the throne is hereditary meaning that family members pass it from one to another. In an elected one, people choose who the monarch will be. It's something like an archaic presidential run but the monarch has way more power than a president has nowadays. This was common in some Arabic countries in history.
2. Africans mixed ancestor worship with Islam or Christianity.
Anti-communist ideas being spread.
