A.Too much or too little rain may have ruined crops, creating food shortages.
A.Earthquakes or erupting volcanoes may have destroyed communities.
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It is not C, because silt makes rivers even MORE salty, and does not give clean water
It is not D, because long-term farming wears out the farmland, and you will not be able to grow more than you used to, because the nutrients inside the soil is dwindeling
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