Answer:
(D). A word that has an opposite meaning.
Step-by-step explanation:
Context clues are the 'hidden' facts or information in a sentence or text which holds the key to the wholesome understanding of the passage or sentence. They are used by writers in making use of new, less commonly known words.
An antonym is the word that is the opposite of what has been stated. It defines exactly the opposite of what is meant. So for an antonym to be a context clue, it will be best to understand what antonym means first. And accordingly, it will be found that an antonym as a context clue is a word that gives the meaning opposite to what has been stated in the sentence.