The correct answer is C. Grammar.
A grammar is a set of rules that define the structure of sentences in a language. It is a finite set of rules because there are only a finite number of possible sentences that can be formed in a language.
A sign is a physical object or action that represents something else. For example, a stop sign represents the command to stop.
Communication is the process of exchanging information between two or more people. It can be done through speech, writing, sign language, or other means.
A phrase is a group of words that together have a meaning. For example, the phrase “the cat sat on the mat” has a meaning that is different from the meaning of the
words “the,” “cat,” “sat,” and “mat” when they are not grouped together.