b. radioactivity
The process by which atomic nuclei spontaneously decay is called radioactive decay. Explanation : This is also known as nuclear decay on a general basis In this process of radioactivity the unstable atomic nucleus loses energy .
Blood flows to the brain through the internal carotid and vertebral arteries and away from the brain through the internal jugular vein. The internal carotid artery supplies the brain, while the external carotid nourishes other portions of the head, such as the face, skull, scalp and the meninges. The vertebral arteries provide supply to the upper spinal cord, brainstem, cerebellum, and the posterior part of the brain.
