This would be a perfect example of the system of barter as you are trading one book for the other. You can see from here what barter is, a trading system which involves direct exchange of goods without some kind of medium of exchange, for example money. Services can also be traded this way.
The correct answer is D. Living according to ones purpose
King George III withdrew all British troops from the colonies.
Explanation:
The Portuguese mostly settled in South America, however, Spain was ruling over most of South America and the Caribbeans.
The immediate cause of World War I that made the aforementioned items come into play (alliances, imperialism, militarism, nationalism) was the assassination of Archduke Franz Ferdinand of Austria-Hungary. ... This assassination led to Austria-Hungary declaring war on Serbia.