Imbibition/diffusion is the movement of substances from the region of their higher concentration to the region of lower concentration.

Explanation

### Step-by-Step Solution:

1. **Understanding the Terms**:
- Imbibition and diffusion are two processes related to the movement of substances.
- Imbibition refers to the absorption of water by solids or colloids, while diffusion is the movement of substances from a region of higher concentration to a region of lower concentration.

2. **Defining Diffusion**:
- Diffusion is a passive transport mechanism. This means it does not require energy (ATP) to occur.
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