(A) Stop word
Words like 'an', 'is', 'the' that appear frequently in a corpus but add negligible value to the text are called Stop words.
As per the textbook (Chapter 6), stop words are defined as words with frequent occurrence in the corpus that have negligible value and are often removed during preprocessing. The MCQ option (A) directly matches this definition. Students must not confuse stop words with "removable words" — the correct technical term is stop word.