In Which Situation Might You Likely Suspect the Possible Use

In which situation might you likely suspect the possible use of a biological weapon?

A) Hospitals report an unusually high number of ill patients, each with different symptoms.
B) A school is quickly swept by a flu-like illness, resulting in canceled classes.
C) Residents report an alarming number of crows appearing sick or dying.
D) A resident reports that their previously healthy dog suddenly became ill and died.