A : Lichens do not grow in polluted area having `SO_(2)`.
R : Lichens secrete carbonic acid and oxalic acid on barren rocks.
A. If both assertion & reason are true and the reason is the correct explanation of the assertion
B. If both assertion & reason are true but the reason is not the correct explanation of the assertion
C. If assertion is true statement but reason is false
D. If both assertion and reason are false statements