Which of the following is not a primary source?

How did inca develop their road system? a) they used mortar to hold the stones together.b) they built suspension bridges over rivers. c) they mixed copper and stone together to make the blocks.d) they laid roads in the cities, not in the less densely populated deserts.

The information box says that the han added 4,000 miles of wall.refer to the mileage scale.how can this be true?

In the supply-and-demand schedule shown above, the equilibrium price for cell phones is $25 $100 $200