In __(i)__, protoxylem lies towards periphery and metaxylem lies towards centre. Such an arrangement of primary xylem is called as __(ii)__

Options

A. a) `{:("Column I","Column II"),("stems","endarch"):}`
B. b) `{:("Column I","Column II"),("stems","exarch"):}`
C. c) `{:("Column I","Column II"),("roots","endarch"):}`
D. d) `{:("Column I","Column II"),("roots","exarch"):}`

Explanation

To answer the question, we need to fill in the blanks based on the arrangement of protoxylem and metaxylem in plants.

### Step-by-Step Solution:

1. **Identify the Arrangement of Xylem**:
- The question states that protoxylem lies towards the periphery and metaxylem lies towards the center. This specific arrangement is characteristic of certain plant structures.

2. **Determine the Type of Plant Structure**:
- This arrangement (protoxylem on the outside and metaxylem on the inside) is typically found in the roots of plants. In roots, the protoxylem develops from the outermost layer of the procambium, while the metaxylem develops from the inner layers.

3. **Identify the Type of Development**:
- The arrangement described in the question is known as "exarch" development. In exarch development, the protoxylem is positioned towards the periphery, and the metaxylem is located towards the center.

4. **Fill in the Blanks**:
- Therefore, the first blank (i) should be filled with "roots", and the second blank (ii) should be filled with "exarch".

### Final Answer:
In **(i)**, protoxylem lies towards periphery and metaxylem lies towards centre. Such an arrangement of primary xylem is called as **(ii)** exarch.