The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
Air that enters the pleural space during inspiration but is unable to exit during expiration creates a condition called Pneumothorax.
<h3>What is Pneumothorax?</h3>
An abnormal buildup of air in the pleural space between the lung and the chest wall is known as a pneumothorax. Shortness of breath and quick, acute, one-sided chest discomfort are common symptoms . A tension pneumothorax happens when an area of injured tissue forms a one-way valve, increasing the amount of air in the gap between the chest wall and the lungs. As a result, there may be an oxygen deficiency that worsens with time and low blood pressure. Obstructive shock is a type of shock that results from this and can be lethal if left untreated. A pneumothorax can very infrequently affect both lungs. Although the term "collapsed lung" can also refer to atelectasis, it is frequently used to describe it.
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The answer to the question is D
