What is the difference between a "prefix" and a "suffix"?

A prefix is a morpheme that is added to the beginning of a word, while a suffix is a morpheme that is added to the end of a word. This distinction is fundamental in understanding word formation in the English language. By adding prefixes and suffixes, the meaning and grammatical function of root words can be altered. For example, adding the prefix "un-" to the verb "happy" creates "unhappy," which changes the meaning to the opposite. Similarly, adding the suffix "-ing" to the verb "run" forms "running," which indicates an ongoing action. This clear difference in placement is what makes the correct answer distinct.

Other options, while they may touch on concepts related to prefixes and suffixes, do not accurately describe the fundamental differences in their definitions and usages, which is why they would not be suitable answers.