How many tons of Mainz was produced in the Colombian exchange

Explanation:

The Columbian exchange, also known as the Columbian interchange, named after Christopher Columbus, was the widespread transfer of plants, animals, culture, human populations, technology, diseases, and ideas between the Americas, West Africa, and the Old World in the 15th and 16th centuries. It also relates to European colonization and trade following Christopher Columbus's 1492 voyage.[1] Invasive species, including communicable diseases, were a byproduct of the exchange. The changes in agriculture significantly altered global populations. The most significant immediate impact of the Columbian exchange was the cultural exchanges and the transfer of people (both free and enslaved) between continents.

d.prevent the spread of communism outside of eastern europe.

d. china

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d is the best choice