Imbibition is -

Options

A. Faciliated diffusion
B. An active transport
C. Primary active transport
D. Diffusion

Answer

**Step-by-Step Solution:**

1. **Definition of Imbibition**: Imbibition is the process through which water is absorbed by solids, particularly those that are hydrophilic (water-attracting) and porous (having small holes or spaces).

2. **Characteristics of Solids in Imbibition**: The solids involved in imbibition must be hydrophilic and porous. Hydrophilic materials have a strong affinity for water, allowing them to attract and hold water molecules.

3. **Mechanism of Imbibition**: During imbibition, water moves into the solid along a concentration gradient. This means that water moves from an area of higher concentration (in the surrounding water) to an area of lower concentration (inside the solid).

4. **Relation to Diffusion**: Imbibition is a type of diffusion. However, it differs from facilitated diffusion and active transport because it does not involve a membrane. In facilitated diffusion, specific carrier proteins help transport substances across a membrane, while active transport requires energy to move substances against their concentration gradient.

5. **Conclusion**: Given the options provided (facilitated diffusion, active transport, primary active transport, and diffusion), the correct classification of imbibition is that it is a type of diffusion.

**Final Answer**: Imbibition is a type of diffusion.

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