In the study of history the available documents for studying a certain period is unchanging over time.
Option: B
Explanation:
History is the study of events and phenomena over space and time. Space means where the particular incident is taking place. Time means the period of occurrence of particular event. A certain period suppose the period of sultanate or mughal empire requires some documents, records to be studied in detail.
And these available documents, records can never be changed over time. History is study of things over changing space and time. Archaeological evidences also keep some valid documents for studying historical events.
I think you would need to tell both leaders to explain their problems then let the other world leaders put their mouths in.
D is the only non fragment sentence here, so it must be correct
Silk Road in Western Han Dynasty (206 BC–24 AD) From 139 BC to 129 BC, Zhang Qian set out on his journey to the Western Regions twice, pioneering the world-famous route.
