Which symptom is indicative of chemical exposure?

The presence of pinpoint pupils, vomiting, and choking is indicative of chemical exposure, especially in the context of specific toxic agents. Pinpoint pupils can be a sign of exposure to certain nerve agents or opioids, which can affect the nervous system's control over pupil size. Vomiting is a common response to various toxins as the body attempts to expel harmful substances. Choking indicates a severe respiratory reaction, which might occur from inhaling toxic fumes or exposure to harmful chemicals. This combination of symptoms highlights the acute effects of chemical exposure, which often require immediate medical attention.

The other symptoms mentioned in the other choices typically align with different health conditions or reactions, which may not necessarily point towards chemical exposure directly. For example, nausea and fatigue could be seen in many types of illnesses, including infections or environmental factors, while flu-like symptoms might suggest a viral infection rather than chemical exposure. Lastly, a rash progressing to pustules might indicate an allergic reaction or infection rather than direct chemical exposure.