Which of the following best describes the nature of acute effects?

Acute effects refer to health impacts that occur shortly after exposure to a hazardous substance, typically within a short time frame, often immediately or soon after contact. These symptoms are characterized by their brevity in duration; they may be severe but resolve relatively quickly once the exposure stops or is minimized.

In contrast, the other options illustrate chronic or long-term effects rather than acute. Long-lasting symptoms requiring extensive treatment involve prolonged health effects that may arise from ongoing exposure to a hazard. Symptoms developing after months of exposure point to cumulative effects typical of chronic exposure rather than acute impacts. Lastly, gradual deterioration over several weeks also describes a more slow-onset health issue rather than the immediate response typical of acute effects. Therefore, the best description of acute effects is those that yield short duration symptoms resulting from immediate exposure.