The general relative order of anion exchange is ____?

Correct option is D

Anion exchange capacity (AEC) is the soil’s ability to hold and exchange negatively charged ions (anions). The relative order depends on the charge density and affinity of soil colloids, with H₂PO₄⁻ having the highest affinity, followed by SO₄²⁻, NO₃⁻, and OH⁻.