Which action exemplifies a tact response?

The action that exemplifies a tact response is saying "dog" when a dog is present. A tact is a type of verbal operant in which a speaker labels or identifies something in the environment, which is a response to a non-verbal stimulus. In this instance, the individual observes the dog and appropriately uses the word "dog" to label the object they see. This demonstrates an understanding of the world around them and allows for sharing information or observations with others.

Other actions listed do not fit the definition of a tact. Asking for a snack involves seeking a specific item, which is more aligned with a mand, where the speaker requests. Repeating a phrase back is an example of echolalia and does not involve labeling or identifying; it is simply repeating what has been heard. Filling in a blank in a sentence resembles responding to prompts or completing a task, which is not a direct observation or labeling of an environmental element. Thus, the response of saying "dog" accurately demonstrates the essence of a tact.