The oldest layer of secondary phloem is

Options

A. Outside the cork cambium
B. Inside the vascular cambium
C. Inside the primary phloem
D. Immediately out side the vascular cambium

Answer

To answer the question about the oldest layer of secondary phloem, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Phloem**:
- Phloem is a type of vascular tissue in plants responsible for the transport of nutrients, particularly sugars produced through photosynthesis.

2. **Identify the Layers of Phloem**:
- Phloem consists of different layers, including primary phloem (formed during primary growth) and secondary phloem (formed during secondary growth).

3. **Locate the Youngest and Oldest Secondary Phloem**:
- The youngest secondary phloem is located outside the vascular cambium, while the oldest secondary phloem is situated inside the primary phloem.

4. **Determine the Correct Answer**:
- Since the question asks for the oldest layer of secondary phloem, we conclude that it is located inside the primary phloem.

5. **Review Other Options**:
- The other options provided (outside the cork cambium, inside the vascular cambium, and immediately outside the vascular cambium) are incorrect based on the established positions of the layers.

### Final Answer:
The oldest layer of secondary phloem is **inside the primary phloem**.

---