Which cells can replace themselves or recover to some extent from radiation exposure if the dose is not excessive?

The ability of certain cells to replace themselves or recover from radiation exposure is primarily attributed to their inherent regenerative capacity. Sperm cells have a well-known ability to regenerate and replace themselves through spermatogenesis, which occurs continuously in the male reproductive system. If sperm cells are exposed to radiation, they have the potential to recover, provided the dose of radiation is not excessive.

On the other hand, nerve cells, or neurons, have a more limited capacity for regeneration compared to sperm cells. While it is true that some neurogenesis can occur in certain areas of the brain, the overall capacity of nerve cells to recover from radiation damage is significantly less than that of sperm cells. However, they can still exhibit some degree of resilience and repair mechanisms that allow for limited recovery in less severe cases of exposure.

Thus, the combination of these two types of cells—sperm cells with a robust regenerative capacity and nerve cells with limited recovery ability—leads to the conclusion that both sperm and nerve cells have the potential to replace or recover from radiation exposure, albeit to differing extents. This makes the option indicating both cell types the most accurate choice in the context of the question.