3) Heat and gases contracted within a nubula
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Aerospace, aviation, and defense
Answer:
option d Variations in local temperatures
Explanation:
<em>this </em><em>might </em><em>be </em><em>ur </em><em>answer </em><em>I </em><em>guess </em>
But roughly 2.45 billion years ago, the isotopic ratio of sulfur transformed, indicating that for the first time oxygen was becoming a significant component of Earth's atmosphere, according to a <span>2000 paper in Science</span>. At roughly the same time (and for eons thereafter), oxidized iron began to appear in ancient soils and bands of iron were deposited on the seafloor, a product of reactions with oxygen in the seawater."What it looks like is that oxygen was first produced somewhere around 2.7 billion to 2.8 billon years ago."It looks as if there's a significant time interval between the appearance of oxygen-producing organisms and the actual oxygenation of the atmosphere."
Maximum Thrift is a method / philosophy that considers the shortest tree (in number of transformation steps) the best hypothesis about the phylogenetic relationship of a given set of terminals. Transformation step is the cost attributed to the change of character state in a given branch of the tree, be it the change from one nucleotide base to another, amino acids, or the color of an animal's iris. The fewer transformations, the shorter the tree, and therefore the more parsimonious. In this method, what programs do is to investigate as many alternative topologies as possible (or all if their array has less than 25 terminals; see more details below) given their character array. Each will be measured, and the shorter (optimal) trees will be retained as the most parsimonious result.