If some cells in an adult mammal are lost, they are lost forever and cannot be replaced. Which of the following cell types have such a limitation? Your answer would be a string composed of a subset of the letters A to E in alphabetical order, e.g. AE.
(A) Photoreceptive epithelium of the retina
(B) ? Cells of pancreatic islets
(C) Hepatocytes of the liver
(D) Auditory epithelium of the inner ear
(E) Olfactory epithelium of the nose