Which of the following is a true statement about the countries of North America?

The population of each country tends to settle in the mountainous areas.
The countries do not have valuable natural resources such as oil.
They trade the most with each other because transportation is easier.
They have climate patterns that limit them to making few products.

What is the main difference between primary and secondary sources? a. primary sources are historical documents, and secondary sources are modern-day documents. b. primary sources are derived from museums and archives, and secondary sources are created by history students and academics. c. primary sources are found in ancient places with a rich history, and secondary sources are found in historical journals and blogs. d. primary sources are created during a particular historical era, and secondary sources are created by studying primary sources.