Alfred Crosby said he came upon the expression "Columbian Exchange" because

The impact of living organisms traded between the Old and the New World.

Explanation:

Historian Alfred W. Crosby came with the term “Columbian Exchange” to describe the impacts of the living organisms begin in the 15th century. With the discovery of America, in 1492, led the beginning of the Exchange between two continents. There was an exchange of native animals, plants, and diseases moving back and forth across the oceans. Europeans made trading connections with the natives and established colonies. The invaders came in with infectious diseases in the New World, that led to the decline of the entire civilizations. The Native American died with coming connecting with chickenpox, smallpox, scarlet fever, cholera, malaria, measles, etc.

union blockade

explanation:

the union blockade in the american civil war was a naval strategy by the united states to prevent the confederacy from trading.

the blockade was proclaimed by president abraham lincoln in april 1861, and required the monitoring of 3,500 miles (5,600 km) of atlantic and gulf coastline, including 12 major ports, notably new orleans and mobile. those blockade runners fast enough to evade the union navy could only carry a small fraction of the supplies needed. they were operated largely by british citizens, making use of neutral ports such as havana, nassau and bermuda. the union commissioned around 500 ships, which destroyed or captured about 1,500 blockade runners over the course of the war.

hr2520 is the patient's act. there is required the secretary of health to summon a committee to develop a national strategic plan of prevention. this committee has forth provisions that make possible for the govern entities to acquire private health insurance services.

is easier to keep this hr2520 as federal, because that way the secretary of health has centralized power to deal with private insurance companies and the federas government has more ways and power to negotiate with them, than doing this process state by state in their specific terms.