The Earth was formed approximately $4500$ million years ago.

The origin of life occurred in .....

Who demonstrated that life comes only from pre-existing life?

Read the following statements and find out the correct ones:
$A.$ Spontaneous generation theory was approved once and for all.
$B.$ Pasteur showed that in pre-sterilized flasks,life did not come from killed yeast.
$C.$ Oparin observed the formation of amino acids by creating electric discharge in a closed flask.
$D.$ Life appeared $500$ million years before the formation of the earth.

Cyanobacteria originated about how many years ago?

First autotrophs on the primitive earth was/were