Which three major factors contributed to the roman empires decline ?

How did the actions of tsar nicholas 2 and his wife lead to revolution in russia

World war 2 was caused, in part, by which of these factors?

What is the main difference between primary and secondary sources? a. primary sources are historical documents, and secondary sources are modern-day documents. b. primary sources are derived from museums and archives, and secondary sources are created by history students and academics. c. primary sources are found in ancient places with a rich history, and secondary sources are found in historical journals and blogs. d. primary sources are created during a particular historical era, and secondary sources are created by studying primary sources.