A mountain is a single standing one such a Mount Fuji. A mountain range is a chain of mountains such as the Himalayas
This is true.
The definition of megalopolis is that it is a large urban area, huge and densely populated. St. Petersburg is definitely one, however, Miami is relatively small compared to other megalopolises so it might not fall within that category.
The caste system is a rigid social hierarchy based on ethnicity in Hindu society. A democracy is government by the people, where power is often exercised through elected representatives. In a caste system, certain voices are valued more than others, while in a pure democracy, all voices and votes are equal. The caste system is not a system of government, though, so it is inaccurate to make a comparison.
C. Forests of Southern China.