Soil water held tightly to the surface of soil particles and not available to plants is called -

Correct option is A

· Hygroscopic Water:
· This is the thin layer of water tightly bound to soil particles by adhesive forces.
· It is unavailable to plants as the energy required to extract it exceeds the plant's capacity.
· Other Types of Water:
· Capillary Water: Available to plants and held in the micropores of the soil.
· Gravitational Water: Drains freely due to gravity and is not retained in the root zone.
· Groundwater: Stored in aquifers and typically not accessible to roots directly.