Which of these structures is not found in both a monocot root and a dicot stem ?

Options

A. pith
B. polyarch xylem
C. parenchymatous pericycle
D. multi layered parenchymatous cortex

Answer

To solve the question "Which of these structures is not found in both a monocot root and a dicot stem?", we need to analyze the given options and determine which structure is absent in one of the two types of plants.

### Step-by-Step Solution:

1. **Understand the Structures**: We need to identify the structures mentioned in the options and their presence in monocot roots and dicot stems.

2. **Evaluate Each Option**:
- **Option A: Pith**
- **Monocot Root**: Absent
- **Dicot Stem**: Present
- **Conclusion**: Pith is not found in both, so this option is incorrect.

- **Option B: Polyarc Xylem**
- **Monocot Root**: Present
- **Dicot Stem**: Absent
- **Conclusion**: Polyarc xylem is not found in both, so this option is incorrect.

- **Option C: Parenchymatous Pericycle**
- **Monocot Root**: Absent
- **Dicot Stem**: Absent
- **Conclusion**: Parenchymatous pericycle is absent in both, making this option correct for our question.

- **Option D: Multilayered Parenchymatous Cortex**
- **Monocot Root**: Present
- **Dicot Stem**: Present
- **Conclusion**: This structure is found in both, so this option is incorrect.

3. **Final Decision**: The structure that is not found in both a monocot root and a dicot stem is **C: Parenchymatous Pericycle**.

### Answer:
C: Parenchymatous Pericycle