Assertion: Carbon dioxide is a greenhouse gas.
Reason: Carbon dioxide can absorb and re-emit infrared radiation, which can trap heat in the atmosphere.
Both assertion and reason are true, and the reason is the correct explanation of the assertion.
Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
The assertion is true, but the reason is false.
The assertion is false, but the reason is true.
The correct answer is (A) Both assertion and reason are true, and the reason is the correct explanation of the assertion. Carbon dioxide is a greenhouse gas because it can absorb and re-emit infrared radiation, which causes the atmosphere to trap heat and leads to global warming. Hence option A is the correct answer.
Option (B) is incorrect because it incorrectly states that the assertion is correct but the reason is incorrect. Both the assertion and reason are correct. Hence option B is incorrect.
Option (C) is incorrect because it incorrectly states that the assertion is incorrect but the reason is correct. The assertion is correct, and the reason is also correct. Hence option C is incorrect.
Option (D) is incorrect because it incorrectly states that both the assertion and reason are incorrect. Both the assertion and reason are correct. Hence option D is incorrect.