Judge the following sentence according to the criteria given below: Biogenous sediment usually ...

Judge the following sentence according to the criteria given below: Biogenous sediment usually contains abundant calcite below the calcite compensation depth BECAUSE it readily dissolves above the calcite compensation depth.
 
  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.