Assertion: Carbon dioxide is one of the main constituent of greenhouse gases.
Reason: In pregent woman increased `CO` level induced premature birth, spontaneous abortion and deformed birth.
A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true and the reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If assertion is false but reason is true.