Concept:The part labelled I is the spinous process of a vertebra, which mainly serves as an attachment point for muscles.Explanation:The spinous process projects backward from the vertebral arch.Muscles and ligaments attach to this projection.These muscles help in movement and support of the vertebral column.The spinous process does not support or carry the spinal cord.It also does not articulate with adjacent vertebrae.Answer:B. provide surface for attachment of the muscle
