Potential signs of a chemical attack include which of the following?

Potential signs of a chemical attack can manifest in various observable phenomena, and the presence of unusual numbers of dead animals, birds, and/or fish is a significant indicator. This is because chemical agents can have a lethal impact on wildlife, and their sudden deaths in large numbers may signal the presence of hazardous substances in the environment. Wildlife often serves as an early warning system for environmental changes or hazards, including chemical spills or attacks.

Observing an unusual die-off can prompt immediate investigation and response efforts, as it may suggest that dangerous chemicals are present in the air, water, or soil. Identifying such incidents early can be vital for public safety, allowing authorities to assess the situation and take appropriate protective actions for human populations.

The other options might raise suspicion in certain contexts but do not directly correlate to the immediate biological effects on wildlife that are indicative of a chemical attack.