Judge the following sentence according to the criteria given below: The vast majority of carbon ...

Judge the following sentence according to the criteria given below: The vast majority of carbon dioxide in the ocean-atmosphere system is found in the ocean BECAUSE methane is approximately 25 times more effective as a greenhouse gas than carbon
 
  dioxide. A) The assertion and the reason are both correct, and the reason is valid.
  B) The assertion and the reason are both correct, but the reason is invalid.
  C) The assertion is correct, but the reason is incorrect.
  D) The assertion is incorrect, but the reason is correct.
  E) Both the assertion and the reason are incorrect.