Annual rings are the number of:

Options

A. rings of vascular bundles in a monocot stem
B. layers of secondary xylem in a stem
C. internodes in a stem
D. both (b) and (c)

Explanation

**Step-by-Step Solution:**

1. **Understanding Annual Rings:**
- Annual rings, also known as growth rings, are concentric circles that can be observed in the cross-section of woody stems or trunks. They indicate the growth of a tree over the years.

2. **Identifying the Correct Option:**
- The question asks about what annual rings represent. The options provided are:
- A) Rings of vascular bundles in a monocot stem
- B) Layers of secondary xylem in a stem
- C) Internodes in a stem
- D) Both B and C

3. **Analyzing Each Option:**
- **Option A:** Rings of vascular bundles in a monocot stem.
- This option is correct. Annual rings are formed due to the growth patterns of vascular bundles, which include both xylem and phloem.

- **Option B:** Layers of secondary xylem in a stem.
- This option is incorrect. While secondary xylem contributes to the growth of the tree, annual rings are not solely made up of secondary xylem; they include both xylem and phloem.

- **Option C:** Internodes in a stem.
- This option is also incorrect. Internodes are the sections of the stem between nodes and do not contribute to the formation of annual rings.

- **Option D:** Both B and C.
- Since both B and C are incorrect, this option is also incorrect.

4. **Conclusion:**
- The correct answer to the question is **A) Rings of vascular bundles in a monocot stem**. These rings mark the passage of one year in the life of a tree and are influenced by seasonal changes in growth.