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.
It is b) angle B.
The opposite angles of opposite sides are proportional to each other. So the smallest side’s opposite angle will be the smallest angle, and in this case, since the largest side is 12, the opposite angle, B, will be the largest angle.
Also, make sure to check to see if the question is the right subject, hope this helps
Something people think is true is C.Belief
Answer:
Explanation:
Parasympathetic Nervous System. The parasympathetic nervous system is an anatomically defined division of the autonomic nervous system, being that part whose motor components run in cranial nerves III, VII, IX, and X and in the sacral nerves.
