Which of the following represents correct matching set ?

Function	Structure
(a) helps in the movement of body by contraction and relaxation.	(i) Cartilage
(b) Hard structure which forms the skeleton	(ii) Muscles
(c) Part of skeleton which can be bent	(iii) Rib-cage
(d) Joins the chest bone and back bone together to form an enclosure	(iv) Bones

The correct matching set is (a) (ii), (b) (iv), (c) (i), (d) (iii).

Step-by-step Explanation:

1. (a) Helps in the movement of body by contraction and relaxation:
Muscles contract and relax to move the bones to which they are attached, enabling body movement. Therefore, (a) matches with (ii) Muscles.

2. (b) Hard structure which forms the skeleton:
Bones are the hard, rigid structures that make up the framework of the skeleton. Therefore, (b) matches with (iv) Bones.

3. (c) Part of skeleton which can be bent:
Cartilage is a flexible connective tissue found in parts of the skeleton (like the ear lobe, nose tip, and joints) that can be bent without breaking. Therefore, (c) matches with (i) Cartilage.

4. (d) Joins the chest bone and back bone together to form an enclosure:
The rib-cage is formed by ribs connecting the chest bone (sternum) at the front to the backbone (vertebral column) at the back, protecting vital organs inside the chest. Therefore, (d) matches with (iii) Rib-cage.