Which of the following situations requires immediate intervention from an ACO?

Immediate intervention from an Animal Control Officer (ACO) is warranted in situations of neglect, particularly if the animal is showing signs of distress or suffering. When an animal is being neglected in a public place, it raises serious concerns about its welfare and the potential for harm. This scenario suggests that the animal lacks proper care and may be exposed to risks such as inadequate food, water, shelter, or medical attention.

In contrast, a stray dog wandering without a leash may not indicate a pressing emergency; it suggests an animal is lost but may not necessarily be in distress. An animal in a known owner’s yard can often be resolved through communication with the owner, assuming the animal is not in immediate danger. Lastly, a barking but calm dog typically does not require urgent action, as barking does not always indicate a problem—this could simply be normal behavior.

Thus, the situation of neglect signifies an urgent need for intervention to ensure the animal's safety and welfare, making it the correct choice for immediate action.