Lower jaw of man is formed of :

Options

A. One bone
B. Two bones
C. No bone, only muscles
D. Three bones

Explanation

### Step-by-Step Solution:

1. **Identify the Question**: The question asks about the formation of the lower jaw in humans.

2. **Understand the Options**: The options provided include:
- A. One bone
- B. Two bones
- C. No bones, only muscles
- D. Three bones
- E. Pelvic girdle (which consists of ilium, ischium, and pubis)

3. **Determine the Correct Answer**: The lower jaw in humans is formed by a single bone known as the mandible. This bone is the strongest and lowest bone in the human skull and is responsible for holding the lower teeth in their sockets.

4. **Eliminate Incorrect Options**:
- Option B (Two bones) is incorrect because the lower jaw is not formed by two bones.
- Option C (No bones, only muscles) is incorrect as the lower jaw is indeed a bony structure.
- Option D (Three bones) is also incorrect for the same reason.
- Option E (Pelvic girdle) is irrelevant to the question about the lower jaw.

5. **Conclude the Answer**: The correct answer is A. One bone (the mandible).