Why are plants unable to absorb hygroscopic water found in the soil?

Correct answer: It is held very tightly to soil particles by strong attractive forces

Direct answer: B. Hygroscopic water is a very thin film of water held on the surfaces of soil particles, especially fine particles, by strong molecular attraction. The soil-water forces are greater than the suction that ordinary roots can exert, so roots cannot remove this water for transport and photosynthesis. It is therefore present in the soil but physiologically unavailable to most plants. A is wrong because hygroscopic water is not defined by high temperature. C is wrong because it remains adsorbed on particle surfaces rather than simply becoming vapour. D describes gravitational drainage, which affects freely moving water and may produce waterlogging or downward flow; it does not explain tightly held hygroscopic water. Plants can use some capillary water, but not water bound with such force. Memory cue: hygroscopic water is “held, not available.”