C is the correct answer because after the Mycenaean civilization we have a period that lasted between 1 100 BC and 750 BC and is characterized by lack or practically total disappearance of any written records on this period.
A and B are not correct as we have enough material sources that are telling us about the still alive trade links between different areas in that period, which leads to the conclusion that people in that period to function. Thus, D also is not correct.
