Centripetal and centrifugal xylems are important features of
(a) Root and stem, respectively
(b) Exarch and endarch, respectively
(c) Endarch and exarch, respectively
(d) Both a and b

Options

A. Root and stem, respectively
B. Exarch and endarch, respectively
C. Endarch and exarch, respectively
D. Both 1 and 2

Answer

To solve the question regarding the importance of centripetal and centrifugal xylems, we need to analyze the definitions and characteristics of these terms in relation to plant anatomy.

### Step-by-Step Solution:

1. **Understanding Centripetal Xylem**:
- Centripetal xylem refers to the type of xylem that develops from the outside towards the inside of the plant structure. This is typically observed in roots.
- In roots, the xylem is formed in such a way that it grows inward, which is characteristic of exarch development.

2. **Understanding Centrifugal Xylem**:
- Centrifugal xylem, on the other hand, refers to the type of xylem that develops from the inside towards the outside. This is commonly seen in stems.
- In stems, the xylem grows outward, which is characteristic of endarch development.

3. **Relating to the Options**:
- Option (a) states that centripetal xylem is important in roots and centrifugal xylem is important in stems. This aligns with our understanding.
- Option (b) states that centripetal xylem is related to exarch and centrifugal xylem is related to endarch. This is also correct.
- Option (c) reverses the relationship, which is incorrect.
- Option (d) suggests that both (a) and (b) are correct.

4. **Conclusion**:
- Since both options (a) and (b) are correct, the best answer is option (d) - Both a and b.

### Final Answer:
(d) Both a and b