Epiphysial plate is involved in
(a) Formation of bone
(b) Elongation of bone
(c) Thickness of bone
(d) All the above 

Options

A. Formation of bone
B. Elongation of bone
C. Thickness of bone
D. All the above

Answer

To solve the question regarding the involvement of the epiphyseal plate, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Long Bones**: Long bones are composed of three main regions: the epiphysis, metaphysis, and diaphysis. The epiphyseal plate is located between the metaphysis and the epiphysis.

2. **Identify the Composition of the Epiphyseal Plate**: The epiphyseal plate, also known as the growth plate, is made up of hyaline cartilage. This cartilage is crucial for the growth of long bones.

3. **Function of the Epiphyseal Plate**: The primary function of the epiphyseal plate is to facilitate the elongation of bones. This elongation occurs as new cartilage is formed on one side of the plate and is replaced by bone on the other side, leading to an increase in the length of the bone.

4. **Role of Growth Hormone**: The growth hormone, released by the pituitary gland, acts on the epiphyseal plate to promote this process of elongation. This indicates that the epiphyseal plate is specifically involved in the growth of bone length.

5. **Evaluate the Options**:
- **(a) Formation of bone**: While the epiphyseal plate contributes to bone formation indirectly through elongation, it is not primarily responsible for the overall formation of bone.
- **(b) Elongation of bone**: This is the primary function of the epiphyseal plate.
- **(c) Thickness of bone**: The epiphyseal plate does not play a direct role in increasing the thickness of bones; this is more related to the periosteum and other processes.
- **(d) All of the above**: Since options (a) and (c) are not primarily correct, this option is also incorrect.

6. **Conclusion**: Based on the above analysis, the correct answer is **(b) Elongation of bone**.