Assertion: They were cyanobacteria- like organisms, which in ancient time added oxygen to the atmosphere. Reason: Cyanobacteria were photoautotrophic.
A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
B. Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
C. Assertion is true, but Reason is false
D. Assertion is false, but Reason is true