Given below are two statements: one is labelled as Assertion (A) and…

The correct answer is Option (2) → Both (A) and (R) are true but (R) is not the correct explanation of (A).

Assertion (A): Evolutionary biology is the study of history of life forms on earth. — True. A tells us what the subject studies. This is the opening line of the NCERT chapter on evolution.

Reason (R): The geological history of earth closely correlates with the biological history of earth. — True. R is a finding about the earth. Life forms and their common ancestors are found at different periods of earth’s history (epochs, periods and eras), so the history of the rocks and the history of life run together.

Why R does not explain A? A is only a definition of a field of study. R is one of the conclusions reached by that study. A conclusion of a subject cannot be the reason why the subject is defined as it is, so both statements are true but R is not the correct explanation of A.

NCERT Extract:
Evolution – “Evolutionary Biology is the study of history of life forms on earth. What exactly is evolution? To understand the changes in flora and fauna that have occurred over millions of years on earth, we must have an understanding of the context of origin of life, i.e., evolution of earth, of stars and indeed of the universe itself.”
Evolution of Life Forms – A Theory – “… However, these ancestors were present at different periods in the history of earth (epochs, periods and eras). The geological history of earth closely correlates with the biological history of earth. A common permissible conclusion is that earth is very old, not thousand of years as was thought earlier but billions of years old.”