growth/annual rings are formed by the activity of

Options

A. cambium
B. xylem
C. phloem
D. both xylem and phloem

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the formation of growth or annual rings in plants.

2. **Identifying the Relevant Plant Tissue**: The growth rings are primarily associated with the vascular cambium, which is a type of meristematic tissue responsible for secondary growth in woody plants.

3. **Role of Vascular Cambium**: The vascular cambium is responsible for producing secondary xylem (wood) and secondary phloem. However, the formation of annual rings is specifically due to the activity of the cambium.

4. **Seasonal Activity of Cambium**: The activity of the vascular cambium varies with the seasons. It is more active in spring and early summer, leading to the production of larger, lighter-colored cells (spring wood). In contrast, it is less active in autumn, resulting in smaller, darker cells (autumn wood).

5. **Formation of Annual Rings**: The alternating layers of spring wood and autumn wood create visible rings in the wood, known as annual rings. Each complete cycle of growth represents one year.

6. **Conclusion**: Therefore, the correct answer to the question is that growth or annual rings are formed by the activity of the cambium.

### Final Answer:
Growth or annual rings are formed by the activity of **cambium**.

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