Pellicular water:
Pellicular water is the quantum of water contained in the soil pores that cannot be extracted by gravity drainage. It is one of the three types of water present in the soil, along with capillary water and hygroscopic water.

Capillary water:
Capillary water is the water that is held in the soil by capillary forces. It is the water that is available to plants for uptake. Capillary water moves upward through the soil due to capillary action, filling the smaller pores between soil particles. It can be extracted by plants and is essential for their growth and survival.

Hygroscopic water:
Hygroscopic water is the water that is held tightly by the soil particles and cannot be extracted by plants. It is the water that is bound to the soil particles by molecular forces. Hygroscopic water is not available to plants and cannot be easily removed from the soil.

Available water:
Available water is the difference between the field capacity and the wilting point of the soil. Field capacity is the maximum amount of water that the soil can hold against the force of gravity, while the wilting point is the moisture content at which plants are unable to extract water from the soil. Available water is the water that is available to plants for uptake and is essential for their growth and development.

Explanation:
The quantum of water contained in the soil pores that cannot be extracted by gravity drainage is called pellicular water. This water is held in the soil pores by molecular forces and cannot be easily removed from the soil. It is not available to plants for uptake and does not contribute to their growth and development.

Gravity drainage refers to the downward movement of water through the soil under the influence of gravity. However, pellicular water is held so tightly by the soil particles that it cannot be extracted by this process. It remains in the soil pores and does not contribute to the available water for plants.

In contrast, capillary water is the water that is held in the soil by capillary forces and can be extracted by plants. It moves upward through the soil and fills the smaller pores between soil particles. Capillary water is essential for plant growth.

Hygroscopic water is also held tightly by the soil particles, but it is not available to plants and cannot be easily removed from the soil. It is bound to the soil particles by molecular forces.

Therefore, the correct answer is option 'A' - pellicular water.