Syntax refers to the arrangement of words and phrases to create well-formed sentences in a language. It involves the rules and principles that govern the structure of sentences, including word order, punctuation, and sentence formation. The correct definition of syntax is not about the choice of words to create a distinctive tone (option a), nor is it about referencing a part of something to signify the whole (option b), or adding information to a sentence to make it understood (option c). Instead, syntax is about the proper arrangement of words to convey clear and coherent meaning.