What is an example of stopping in speech sound development?

Stopping is a phonological process in which a fricative sound, typically produced with continuous airflow, is replaced by a stop sound, which is produced by completely blocking the airflow. In this context, the example "pun" for "fun" illustrates stopping perfectly because the fricative sound /f/ in "fun" is substituted with the stop sound /p/. This transformation exemplifies how children may simplify their speech by replacing more complex sounds with easier-to-articulate ones.

The other examples do not demonstrate the stopping process; instead, they illustrate different phonological processes or sound substitutions. "Bub" for "bus" involves a substitution of /b/ for /s/ without stopping, "bat" for "cat" represents a substitution of /b/ for /k/, while "tack" for "snack" shows a deletion of the initial consonant cluster rather than a stopping pattern. Therefore, "pun" for "fun" is the correct representation of stopping in speech sound development.