The dose of radiation exposure that can cause severe biological damage is best described as:

The dose of radiation exposure that can cause severe biological damage is best described as high. High doses of radiation are associated with significant harm to living tissues and systems. This level of exposure can result in acute radiation syndrome, which can manifest as symptoms like nausea, vomiting, and even death, depending on the level of exposure and the duration of the radiation.

High doses of radiation impact cellular structures, leading to damage to DNA and other critical components necessary for cellular function and replication. This damage can cause cells to die or can result in mutations, which may lead to cancer or other long-term health complications.

In contrast, minimal exposure is unlikely to cause any noticeable biological effects, while moderate exposure may cause some damage but typically would not lead to severe biological consequences. Variable doses encompass a range of exposure, but without a specific reference to high levels, it lacks the definitive association with severe damage that is present in the other selection. Therefore, high is the most accurate description of the dose associated with severe biological damage.