Final answer:
The continents of North America and South America were called the 'New World' by Europeans in the 1600s because these continents had been unknown to the people of Europe, not because they were unpopulated.
Step-by-step explanation:
The continents of North America and South America were called the New World by Europeans in the 1600s because these continents had been unknown to the people of Europe.
Notably, it is a misconception that these landmasses were unoccupied before European arrival, as they were inhabited by millions of people, boasting a variety of complex societies, such as the Aztec, Maya, and Inca empires, as well as tribes in what is now the United States.
Amerigo Vespucci's writings, particularly his Mundus Novus, dispelled earlier assumptions held by some Europeans that the lands were part of Asia and established the concept of the Americas as a newly discovered continent. The term 'New World' was a result of European exploration led by figures like Columbus and Vespucci, who introduced the European perspective of the Americas as a fresh discovery.
Thus, the correct answer to why Europeans called the continents of North America and South America the New World is option B: these continents had been unknown to the people of Europe.