I'm assuming you meant subsistence farming? If so then yes, it would be a large problem because they would then not have enough food to feed themselves.
The cretaceous-tertiary mass extinction was apparently caused by a meteorite that struck Yucatan Peninsule in Mexico
The one answer that I am missing among the options, but which is the correct one is: the geography of the region ( I assume that that's what was instead of the "7" in the first option).
It was very mountainous, with valleys and islands on which people lived -meaning there was a natural separation between the different settlements.
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