In Porcupine , hair of the back are modified into

Options

A. Scales
B. Horns
C. Spines
D. Plates .

Answer

**Step-by-Step Solution:**

1. **Understanding Mammalian Characteristics**:
- All mammals possess hair at some stage of their life, which is a defining characteristic of the class Mammalia.

2. **Modification of Hair**:
- In some mammals, hair can be modified into different structures that serve various functions, including offense and defense.

3. **Identifying the Porcupine's Hair Modification**:
- In the case of the porcupine, the hairs on its back are specifically modified for defense.

4. **Determining the Correct Modification**:
- The options given are scales, horns, spines, and pleats. Among these, spines are the correct modification of hair in porcupines.

5. **Description of Spines**:
- The spines of porcupines are stiffened and enlarged modifications of hair. They are covered with keratin and can easily fall out or break off when threatened.

6. **Conclusion**:
- Therefore, the correct answer to the question is that in porcupines, the hair of the back is modified into **spines**.

**Final Answer**: The hair of the back in porcupines is modified into **spines**.

---