Correct Answer: Brain cells

Solution : The correct option is Brain cells.

The central nervous system's neurons, or nerve cells (including the brain and spinal cord), have the least regeneration ability in the human body. Neurons, unlike many other cells, have a restricted ability to conduct mitosis (cell division), and their ability to regenerate after injury or damage is severely limited. This is one of the reasons why nervous system injuries, such as spinal cord injuries, can have serious and sometimes lifelong consequences for function and movement.