[A]: The secondary phloem constitutes a less prominent part of the tree trunk than the secondary xylem
[R] : The amount of Phloem produced by the cambium is smaller than that of secondary

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

To solve the question regarding the prominence of secondary phloem compared to secondary xylem in the tree trunk, we can break down the reasoning into clear steps:

### Step-by-Step Solution:

1. **Understanding the Structure of the Tree Trunk**:
- The tree trunk is made up of various tissues, including vascular tissues such as xylem and phloem.
- Xylem is responsible for the transport of water and minerals, while phloem transports food.

**Hint**: Recall the functions of xylem and phloem in plants.

2. **Role of Vascular Cambium**:
- The vascular cambium is a layer of meristematic tissue that is responsible for secondary growth in plants.
- It produces secondary xylem towards the inside (towards the pith) and secondary phloem towards the outside.

**Hint**: Remember that vascular cambium is crucial for the secondary growth of the plant.

3. **Comparison of Secondary Xylem and Phloem Production**:
- The cambium produces more secondary xylem than secondary phloem.
- As the tree grows, the accumulation of secondary xylem leads to the formation of wood, which is a compact mass.

**Hint**: Think about how the growth patterns of xylem and phloem differ over time.

4. **Analyzing the Statements**:
- The first statement (A) claims that secondary phloem constitutes a less prominent part of the tree trunk than secondary xylem. This is true because the wood (secondary xylem) is much more substantial.
- The reason (R) states that the amount of phloem produced by the cambium is smaller than that of secondary xylem, which is also true.

**Hint**: Evaluate the truth of each statement based on the anatomical structure discussed.

5. **Conclusion**:
- Since both statements A and R are true, and R provides a correct explanation for A, we conclude that the correct answer is that both A and R are true, and R is the correct explanation of A.

**Hint**: Look for logical connections between the statements to determine their relationship.

### Final Answer:
Both A and R are true, and R is the correct explanation of A.