Question

Life originated how many years ago?
(a)8 billion years ago
(b)6 billion years ago
(c)4 billion years ago
(d)1billion years ago

Answer 1

Hint During that period Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. It has been thought by scientists that a giant collision with a planet-sized body named Theia occurred which led to the formation of the Moon.

Complete answer:
Around 4 billion years ago life on earth originated. The processes by which living and fossil organisms have evolved has been traced as the evolutionary history of life on Earth, from the very earliest emergence of life to the present situation.
-The similarities among all known present-day species indicate that they have been originated from a common ancestor through the process of evolution.
-The dominant form of life in the early Archean were the microbial mats of coexisting bacteria and archaea.
-Epoch and many of the major steps are thought to have taken place in this environment, during the early evolution.
-Photosynthetic organisms appeared between 3.2 and 2.4 billion years ago and commenced enriching the atmosphere with oxygen.
-Until about 580 million years ago the life remained mostly small and microscopic, but when complex multicellular life arose, they developed over time and culminated within the Cambrian Explosion about 541 million years ago.
-The period of 4.6 billion years ago to 3.8 billion years ago is termed the Azoic era when the primitive earth conditions were too harsh to sustain anybody.
-During this period, the earth’s temperature cooled down and the ocean and atmosphere were formed.
-The Archaeozoic era is marked by the looks of the primary body within the hot soup of the primitive ocean which dates back around 4 billion years ago.
-The first life forms were prokaryotic, chemoheterotrophic, and anaerobic organisms. This sudden diversification of life forms produced most of the main phyla known today and divided the Proterozoic from the Cambrian of the Paleozoic.
-It has been estimated that ${ 99 }$% of all the species that have lived on Earth, over five billion years, nowadays have become extinct.
-Estimates on the amount of Earth's current species range from 10 million to 14 million, of which about 1.2 million are documented, but over ${ 86 }$% haven't been described. However, it had been recently claimed that 1 trillion species currently survive Earth, with only one-thousandth of ${ 1 }$% one percent described.

So, the correct answer is,’4 billion years ago’.

Note:
-The similarities among all known present-day species indicate that they have been originated from a common ancestor through the process of evolution.
-Photosynthetic organisms appeared between 3.2 and 2.4 billion years ago and commenced enriching the atmosphere with oxygen.
-It has been estimated that ${ 99 }$% of all the species that have lived on Earth, over five billion years, nowadays have become extinct.