Correct Option: A

Alkali, or alkaline, soils are clay soils with high pH(>8.5), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate which causes the soil to swell and difficult to clarify/settle.