To answer this question, we need to understand the concept of cell replacement in different parts of the body.
Option A) Kidneys - This option is correct because cells in the kidneys are not replaced when they die. The kidneys are vital organs responsible for filtering waste and excess fluid from the blood to form urine. The cells in the kidneys, known as nephrons, do not have the ability to regenerate or replace themselves once they are damaged or destroyed. Therefore, when kidney cells die, they are not replaced.
Option B) Skin - This option is incorrect because cells in the skin are constantly replaced when they die. The outermost layer of the skin, called the epidermis, is composed of constantly dividing cells. As the older cells move towards the surface, they die and are sloughed off, while new cells are continuously produced in the lower layers of the epidermis.
Option C) Muscles - This option is incorrect because cells in muscles can be replaced when they die. Muscles are made up of muscle fibers, which can be repaired and regenerated after injury or damage. While the rate of cell replacement in muscles may be slower compared to some other tissues, such as the skin, the body does have the ability to replace damaged muscle cells to some extent.
Option D) Brain - This option is incorrect because cells in the brain are not typically replaced when they die. The brain contains specialized cells called neurons, which are responsible for transmitting signals and information. Unlike some other cells in the body, neurons generally do not regenerate or replace themselves when they die. However, certain areas of the brain may have limited neurogenesis, which refers to the production of new neurons. Nonetheless, the overall replacement of brain cells is relatively limited.
Therefore, the correct answer is A) Kidneys.