Final answer:
The Medieval Period was once called the "Dark Ages" due to a misconception by Renaissance humanists about a decline in Classical antiquity's achievements, primarily because fewer written records from that period survived.
Step-by-step explanation:
The term "Dark Ages" was once used to describe the Medieval Period, especially the time shortly after the fall of the Roman Empire, because Renaissance humanists saw it as a time of cultural and intellectual decline relative to the achievements of Classical antiquity. They believed this era represented a significant loss of classical learning and artistic refinement. However, the notion of the Dark Ages is now largely rejected by modern scholars, who recognize the misconceptions of earlier historians and acknowledge that the period was, in its own right, rich in cultural, social, and technological advancements.
In response to the options provided, the most accurate reason the Medieval Period was once considered the "Dark Ages" is Option 2: A limited amount of written records survived. This scarcity of records has contributed to the perception of a lack of progress during the time. While it is true that there were hardships, such as a lack of centralized governance and consistent warfare, there were also significant developments in areas like engineering and architecture, including the construction of cathedrals and castles. Moreover, there were advances in other areas such as the establishment of universities and the gradual increase in literacy.