The process by which plants becomes woody is

Options

A. Impregnation
B. Lignification
C. Fossilization
D. Calcification

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the process that makes plants woody. This indicates a focus on the structural changes that occur in plants, particularly in relation to their tissues.

2. **Identifying the Options**: The options provided are:
- A) Impregnation
- B) Lignification
- C) Fertilization
- D) Calcification

3. **Analyzing Each Option**:
- **Impregnation**: This term generally refers to the process of saturating a material with a substance, often used in contexts like preservation of fossils, not related to making plants woody.
- **Lignification**: This is the process where lignin, a complex organic polymer, is deposited in the cell walls of plants. This process strengthens the plant tissues and contributes to their woody characteristics.
- **Fertilization**: This is the process of fusion of male and female gametes, leading to the formation of seeds, and does not relate to the woodiness of plants.
- **Calcification**: This refers to the accumulation of calcium salts in body tissues, which is not related to the woody structure of plants.

4. **Conclusion**: Based on the analysis, the correct answer is **B) Lignification**. This process involves the deposition of lignin, which provides strength and waterproofing to the plant tissues, resulting in wood formation.

**Final Answer**: The process by which plants become woody is called **lignification**.

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