I believe the answer is B
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.
Taking into account the statement above "Which was a feature of the relationship between the soviet union and the united states in the era leading up to détente?"
The answer is the Arms race. Hope this helps.
The Louisiana Purchase, which was purchased by the United States from France, greatly impacted the development of the US in that it gave the US a large area of land for extremely cheap.
