Which continent is known as the 'Dark Continent'?

The term 'Dark Continent' is historically used to refer to Africa, primarily during the 19th century. This label emerged during the age of exploration when much of Africa was largely unknown to Europeans, leading to misconceptions and stereotypes about the continent. The phrase reflects the combination of the physical vastness of Africa, the exoticism perceived by outsiders, and the lack of geographical, cultural, and historical understanding at that time.

The other options do not fit this context. Asia, while vast and diverse, has been extensively documented and explored throughout history. South America has also been well-studied, especially following European colonization. Australia is similarly recognized and documented, known for its unique ecosystem and indigenous cultures. Hence, Africa remains the continent that was specifically referred to as the 'Dark Continent' due to the historical context and European perceptions during the exploration period.