Which type of cell is least affected by radiation exposure?

Muscle fibers are least affected by radiation exposure because they are more differentiated and less actively dividing compared to other cell types. In general, cells that are actively dividing, such as skin cells and bone marrow cells, are more sensitive to radiation because the DNA within these cells is more susceptible to damage during replication. Skin cells have a high turnover rate as they are constantly shed and replaced, making them more vulnerable to the harmful effects of radiation. Bone marrow cells, which are responsible for producing blood cells, are also highly sensitive due to their rapid division. In contrast, nerve cells are typically post-mitotic and do not divide, which can provide them some protection from radiation damage, but they can still be affected due to the intricacy of their structure and functions. Muscle fibers, especially mature ones, do not regularly undergo division and are generally more resilient to radiation damage, making them the least affected among the options presented.