Which of the following describes early effects of radiation?

The early effects of radiation are best characterized as deterministic and threshold. Deterministic effects are those that have a clear cause-and-effect relationship, meaning that as the dose of radiation increases, the severity of the effect becomes more pronounced. This is in contrast to stochastic effects, which are random and do not have a threshold; even at low levels of exposure, they could potentially occur.

Threshold indicates that there is a specific amount of radiation that must be exceeded before the effects become evident. For early effects, this threshold corresponds to a high enough dose where signs of damage manifest relatively soon after exposure. Common examples of deterministic effects include radiation burns, radiation sickness, and acute injuries, which tend to occur quickly and have a predictable risk based on the amount of exposure.

The other descriptions do not accurately capture the nature of early radiation effects. Stochastic effects, while possible at various dose levels without a defined minimum, pertain more to long-term consequences rather than immediate outcomes. Acute and progressive could imply a variety of conditions that may not specifically connect to early radiation exposure, while chronic and minimal suggests a long-term, less critical scenario that doesn't apply to the immediate effects seen shortly after significant radiation exposure.