What do we call common letter combinations found at the end of words?

The correct choice identifies common letter combinations at the end of words as suffixes. Suffixes are groups of letters added to the end of a word that modify its meaning or grammatical function. For instance, adding "-ing" to a verb creates a present participle (e.g., "run" becomes "running"). On the other hand, prefixes are added to the beginning of words, roots serve as the base form of words without any affixes, and stems refer to the main part of a word that provides its core meaning, which can include both roots and suffixes. Understanding suffixes is essential for word formation and recognizing word meanings, making this choice the most accurate in defining letter combinations at the end of words.