The diagram below shows that the Roman Republic contributed to the development of democratic principles.

A diagram showing two boxes with an arrow pointing from the first box to the second box. The first box is labeled with a question mark, and the second box is labeled 'The Bill of Rights.'

Which phrase completes the diagram?

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 a. primary sources are historical documents, and secondary sources are modern-day documents.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.