$A$ : During evolution the early time period was without ozone layer.
$R$ : Ozone layer absorbs $U.V.$ rays to some extent.

First autotrophs on the primitive earth was/were

The complex organic compounds that may have first evolved in the direction of origin of life on earth, may have been

Describe various theories of origin of life.
 

Assertion : The primitive atmosphere was reducing one i.e., without oxygen.

Reason : In the primitive atmosphere, oxygen was involved in forming ozone