Final answer:
The correct answer is a) Anterior and posterior spinal arteries. These arteries are derived from the vertebral arteries, which supply blood to the anterior surface of the spinal cord and contribute to the circle of Willis in the brain.
Step-by-step explanation:
Two sets of arteries are primarily responsible for supplying blood to the spinal cord. These are the anterior and posterior spinal arteries. The anterior spinal artery is a blood vessel that emerges from the branches of the vertebral arteries and runs along the anterior surface of the spinal cord. The vertebral arteries provide blood to the central nervous system (CNS) and are protected as they pass through the cervical vertebrae.
They enter the cranium through the foramen magnum and give rise to several critical branches, including the anterior spinal artery. The vertebral arteries also merge to form the basilar artery, which branches to the brain stem and the cerebellum. Simultaneously, the paired internal carotid arteries along with branches from the basilar artery contribute to the circle of Willis, ensuring the brain's blood supply.