What type of health effects can radiation cause immediately after exposure?

The correct choice pertains to acute health effects, which are the immediate responses that can occur after exposure to a high dose of radiation. Acute health effects are often characterized by symptoms that arise shortly after the exposure, such as nausea, vomiting, skin burns, and in severe cases, radiation sickness, which can occur within hours or days. These effects are associated with substantial doses of radiation and result from direct damage to tissues and biological systems.

In contrast, chronic health effects typically manifest over a longer period of time and are associated with lower levels of radiation exposure. These might include conditions like cancer or cataracts, which develop after extended periods and are influenced by cumulative exposure rather than immediate effects. Delayed onset health effects refer to health issues that arise long after the initial exposure, often complicating diagnosis and response.

Therefore, acute health effects represent the immediate and direct consequences of significant radiation exposure, making it the correct answer for this question.