Self sufficiency of Medival Europe helped to promote Medieval Europe's "Dark Age" because:

A
it slowed trade, travel and the sharing of ideas

B
it encouraged people to challenge religious ideas

C
it led to the mass production of books

D
it kept the serfs bound to their lord's land

The myth of the Middle Ages as a “dark age” does not lie in the fact ... With long-distance trade at a low ebb, European farmers had to be far more self-sufficient, and ... These false ideas are still current partly because historians have only ... Reprints; Advertise: Site / Podcasts · Commenting · Podcast FAQs ...

Explanation:

d is the best answer for this question.

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