What happens to a colony of cells exposed to a dose D?

When a colony of cells is exposed to a specific dose of radiation, what typically occurs is that a fraction of the cell population will be killed, while some cells may survive and continue to proliferate. This is because not all cells within a colony are equally sensitive to radiation; their survival depends on various factors, including their inherent susceptibility, the type of radiation, and the dose received.

In the context of a dose D, certain cells will absorb enough energy to sustain lethal damage, leading to their death, while others may sustain sub-lethal damage that allows them to survive. This variation in response is a fundamental principle of radiation biology. The surviving cells might also have the capability to repair some of the damage, which could contribute to the overall survival of a portion of the colony.

In contrast, the other options suggest absolute outcomes—either total cell death or no effect at all—which disregard the complexity and variability inherent in biological responses to radiation. Therefore, the reality of cellular response to radiation is captured by the idea that a fraction of the cell population dies, while others may survive and continue to proliferate.