Corn potatoes sugar horses smallpox (explain what these have in common)

All the mentioned things are the components of Columbian Exchange trade.  

The Columbian Exchange refers to the trade of animals, goods, and ideas between the Old World, New World, and the trading of slaves from Africa to the New World. In the process, Columbus introduced various animals and goods to the New World, like wheat, sugar, coffee, rice, pigs, horses, and cows.  

He also introduced goods back to the Old World from the New World, like corn, silver, gold, tomatoes, pineapples, chocolate, vanilla, and beans. Unluckily, with the exchange of goods, there was also an exchange of disease, like measles, smallpox, typhus, diphtheria, bubonic plague, influenza, and Scarlett Fever.  

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.

flooding wildfire landslides climate change the factors listed have an immediate effect on the animal populations found in any habitat. the four factors would lead to a death. b emigration. eliminate c immigration. d mutations.