The Schematic Drawing Below Shows the Cross Section of a Crypt

Short Answer

The schematic drawing below shows the cross section of a crypt in the gut epithelium of a mammal. Indicate whether each of the following descriptions better applies to the areas labeled A, B, or C. Your answer would be a four-letter string composed of letters A to C only, e.g. CCBB.

( ) The stem cells reside in this area.
( ) This area contains the most rapidly dividing cells.
( ) Cells in this area would show the least radioactivity following a pulse of tritiated thymidine.
( ) This area contains cells of the innate immune system.