What time period do historians refer to when they discuss the "modern era"?
AThe period between the beginning of river valley civilizations and the start of the Roman Empire
BThe period between the start of the Roman Empire and the end of the Middle Ages
CThe period between the end of the Middle Ages and the present
DThe period between the agricultural revolution and rise of river valley civilizations
AThe period between the beginning of river valley civilizations and the start of the Roman Empire
BThe period between the start of the Roman Empire and the end of the Middle Ages
CThe period between the end of the Middle Ages and the present
DThe period between the agricultural revolution and rise of river valley civilizations
