Cyanobacteria, also known as "blue-green algae", are the unicellular organisms which are able to produce oxygen.
Approximately 540 years ago, the atmosphere was very poor on oxygen. Cyanobacteria are thought to be responsible for the oxidization of the atmosphere back then, in an event known as <em>"The Great Oxygenation Event"</em>. As a result, Earth's life forms suffered drastic changes in their composition, as they evolved from being <em>anaerobic</em> to becoming organisms <em>highly dependant</em> on oxygen. The oxygenation of the atmosphere would eventually provide the adequate environment in order for the <em>Cambrian Explosion</em>, or the first diversification of living organisms, to happen.
For Italy, they were spies who collected top secret knowledge for the Allied Powers. They were U.S. soldiers who fought off the enemy successfully. They were British troops leaving their units to join the enemy.
Answer: Voting increased because many states removed property requirements for voting. These changes meant that most white men could now vote, regardless of their economic status. In addition, several northern states allowed freed African-American men to vote also.
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Answer: Federalism in the United States is the constitutional division of power between U.S. state governments and the federal government of the United States. Since the founding of the country, and particularly with the end of the American Civil War, power shifted away from the states and toward the national government. The progression of federalism includes dual, state-centered, and new federalism.
Explanation:
A) An American railroad tycoon
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