What component is critical in forming new words by attaching to roots?

The correct answer, which identifies the component critical in forming new words by attaching to roots, is "affix." An affix is a linguistic element that is added to a root word to alter its meaning or create a new word. There are two main types of affixes: prefixes, which are added to the beginning of a root, and suffixes, which are added to the end.

Understanding affixes is essential because they expand the vocabulary by forming derivatives, enabling the creation of various forms of a word, such as turning nouns into verbs or adjectives. For example, the root word "act" can become "action" with the addition of the suffix "ion," making "action" a noun that derives from the verb form.

While prefixes and suffixes are specific types of affixes, the term "affix" itself encompasses all such modifications. The term "surfix" is not widely recognized in linguistic terminology, and "interfix" refers to a less common concept used in specific linguistic contexts, further illustrating the superiority of the term "affix" in this context. Thus, "affix" is the most encompassing and correct term that captures the concept of modifying root words in word formation.