Which of these events is pre-columbian? a. the native american population reached 50 million people. b. the spanish introduced horses to native americans. c. the spanish shared tools with native americans. d. the native american population decreased to 8 million people.

The correct answer is A) The Native American population reached 50 million people. 

The event that is pre-Columbian is "Native American population reached 50 million people."

When it is said that the event was pre. Columbian means that it happened before the arrival of Cristopher Columbus to the Americas. According to historians, Columbus arrived in the Americas on October 12, 1492.

So before Columbus arrived, the Native American population reached 50 million people. But after this, the Spanish introduced horses to Native Americans, shared tools with them and the Native American population decreased to 8 million people due to the many that Europeans brought to the Americas, practically unknown to the Native Americans such as influenza, smallpox, malaria, chickenpox, measles, cholera, and typhus, among many others. These diseases killed millions of native American Indians.

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