Which of the following types of cells would be the most radiosensitive?

Stem cells are considered the most radiosensitive type of cells among the choices provided. This increased sensitivity arises from their intrinsic biological characteristics. Stem cells are undifferentiated cells that have the potential to develop into various specialized cell types. Their active nature, particularly in terms of rapid division and growth, makes them more vulnerable to the damaging effects of radiation.

Radiation primarily impacts cells that are actively proliferating, as it can cause DNA damage during cell division. In contrast, differentiated cells, such as those in the central nervous system, liver, and sense organs, tend to have lower rates of division and are therefore more resistant to radiation injury. These differentiated cells are more specialized and have completed their development, rendering them less susceptible to the effects of radiation compared to rapidly dividing stem cells. The biological response to radiation also considers factors such as the cell's capacity to repair DNA damage, which is generally lower in stem cells due to their less specialized functions.

Thus, stem cells' high radiosensitivity can be attributed to their active replication and potential for differentiation, positioning them at a greater risk of radiation-induced damage compared to the other types of cells listed.