A vertical section of wood, at one point shows circular arrangment of annual rings. This is due to

Options

A. a lateral branch
B. sapwood
C. false annual ring
D. abnormal secondary growth

Answer

To answer the question regarding why a vertical section of wood shows a circular arrangement of annual rings, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Annual Rings**: Annual rings are formed due to the activity of the cambium layer in the plant. The cambium is a layer of actively dividing cells that contributes to the secondary growth of the plant.

2. **Role of Cambium**: The cambium produces new layers of xylem (wood) and phloem (bark) each year. The xylem produced in the spring is typically larger and lighter in color, while the xylem produced in the summer is smaller and darker. This difference in growth rates results in the formation of distinct rings, known as annual rings.

3. **Lateral Branching**: The circular arrangement of annual rings can be attributed to lateral branching. As the plant grows, it develops branches laterally, and the cambium continues to produce new xylem layers around the circumference of the stem. This lateral growth results in the circular pattern of the annual rings.

4. **Exclusion of Other Factors**: Other factors such as sapwood, abnormal secondary growth, and monocot arrangements do not contribute to the circular arrangement of annual rings. Sapwood does not form annual rings, and abnormal secondary growth does not lead to a regular pattern of growth.

5. **Conclusion**: Therefore, the circular arrangement of annual rings in a vertical section of wood is primarily due to the activity of the cambium associated with lateral branching.

### Final Answer:
The circular arrangement of annual rings in a vertical section of wood is due to **lateral branching**.

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