What is a spinal cord

The spinal cord is a long, thin, tubular structure.

Explanation:

The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. It encloses the central canal of the spinal cord, which contains cerebrospinal fluid.

answer; polycythemia is the correct answer;