What is true about assertion a and reason r?
Assertion a. The 'biological species' concept helps us to ask how species are formed.
Reason r. The concept of biological species focusses our attention on the question of how reproductive isolation comes about

Options

A. Both a and r are correct but r does not explain a.
B. Both a and r are correct and r is true explanation of a
C. both a and r are not true
D. Only a is true, r is not correct

Answer

D