Answer: a. cervical enlargement.
Explanation:
Cervical enlargement corresponds to the enlargement of the spinal cord. The spinal cord is the origin of the spinal nerves that contribute to an important task of supplying blood to the upper limbs.
The cervical enlargement results in an increase in the volume of the motor cells in the ventral part inside the grey matter. The motor neurons which are sited posteriorly supply to the upper limbs. Those which supply to the distal muscles are situated further posteriorly.
Charles Darwin is considered the father of modern biology, as he influenced more people than any other biologist. Also, evolution by natural selection is the most important part of biology.
The structures that are responsible for the movement of chromosomes to the center of the cell in metaphase is the spindle fibers, the cell attaches the centromeres to the spindle fibers to pull the sister chromatids to the center
In anaphase the sister chromatids are separated at the centromere and are pulled to the opposite poles of the cell by the spindle fibers
An event that could disrupt one or more body systems is a HEAD TRAUMA. When we say head trauma, this is an injury which affects the scalp, the skull or even the brain. When the brain is greatly affected, all of the other systems in the body would not function well since it is the brain is the center of the coordination of the systems. Hope this answer helps.
