Ooo, history! I got this one :D
The stamp act was what required a tax to be paid if you exchanged documents. The act was made by the congress, and it allowed those who paid their tax to have a stamp on their document!
Charlemagne or Charles the great was the king of Franks from 768.
Heat moves through radiation, convection, and conduction.
The answer is d. they are seeking to either support or reject the hypothesis upon which the study was founded