The best definition for prefix is one or more syllables placed in front of a base, or root, word. Option B is correct.
A preffix is defined as an affix placed before a word, base, or another prefix to change a term's meaning, as by making the term negative as un-, by showing repetition, as re- , or by indicating support, as pro-.
Prefixes are added to the beginning of an existing word in order to create a new word with a different meaning.
