Corn crops are very plentiful over the course of the year and there is more corn than people would normally buy. To get rid of the excess supply, farmers need to lower the price of corn so people will buy more of it.

The answer is D. the decline of Europe’s large cities

Every other option is somewhat of a positive thing for a population's growth. The middle class is debatable the best class for a country to have in order to grow, the urbanization is a very good thing, advances in technology and agriculture is extremely good. So therefore, it would be D since the decline of large cities would not fuel industry.

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