Answer:
The answer would be primary
The main <span>connection between the Great Wall and the Mongols was that the Great Wall was erected by the Chinese in an attempt to keep the Mongols out of China (this largely failed). </span>
World war 2 because it tells a lot of events
Answer: TRUE
<span>"Externality" is the term which is used to describe an unintended side effect that affects a third party that had no involvement in the activity that caused the side effect. The side effect is called a positive externality if it benefits the third party, while it is called a negative externality if it is harmful to the third party.</span>