Which type of cell is considered the least sensitive to radiation exposure?

Muscle cells are indeed considered the least sensitive to radiation exposure compared to other types of cells listed. This sensitivity is largely attributed to the regenerative capacity and proliferation rate of different cell types.

Nerve cells, or neurons, have a very limited ability to regenerate and are particularly vulnerable to damage from radiation because they do not typically divide. Skin cells, on the other hand, are highly proliferative and continuously divide, making them more susceptible to radiation damage. Blood cells, especially those in the bone marrow, are also highly sensitive due to their rapid turnover and crucial role in the body's overall function.

Muscle cells, in contrast, are post-mitotic; they do not divide or proliferate at the same rate as skin and blood cells. While they can be affected by radiation exposure, the lower cell turnover rate means that they have a reduced likelihood of sustaining damage that leads to significant functional impairment. Therefore, among the choices provided, muscle cells are the least sensitive to radiation exposure.