The right answer is C. Sulfate
Acid sulfate soil are soils characteristic of certain tannins, characterized by high sulphate levels and high acidity.
Crops are more difficult, and these soils are often more vulnerable to erosion, degradation and salinization.
They are also more vulnerable than soils basic to many pollutions (by heavy metals for example, which are more mobile and bioassimilable in an acid substrate).
