Hood of cobra is formed by

Options

A. Elongation of muscles
B. Contraction and flattening of neck
C. Spreading of ribs of neck region
D. Both A and B

Answer

To answer the question "Hood of cobra is formed by," we need to analyze the options provided and understand the anatomy of the cobra.

### Step-by-Step Solution:

1. **Understanding the Cobra's Hood**: The hood of a cobra is a distinctive feature that allows it to appear larger and more intimidating to potential predators. This is an important survival mechanism for the snake.

2. **Analyzing the Options**:
- **Option A: Elongation of muscles**: While muscles are involved in the movement of the cobra, they do not directly form the hood. Therefore, this option is incorrect.
- **Option B: Contraction and flattening of neck**: This option suggests that the neck muscles contract and flatten to form the hood. However, the hood is not primarily formed by muscle contraction alone. So, this option is also incorrect.
- **Option C: Spreading of ribs of neck region**: The hood is actually formed by the spreading of the ribs in the neck region. The ribs extend and allow the skin to stretch outward, creating the hood appearance. This option is correct.
- **Option D: Both A and B**: Since both options A and B are incorrect, this option is also incorrect.

3. **Conclusion**: The correct answer is **Option C: Spreading of ribs of neck region**. The ribs in the neck area of the cobra play a crucial role in forming the hood by allowing the skin to extend outward.

### Final Answer:
The hood of the cobra is formed by **spreading of ribs of neck region** (Option C).

---