Final answer:
A simile is not an example of a context clue, as it does not help define an unfamiliar word but is rather used for comparison. The other options, antonym and definition, directly help understand word meanings, and hence, are context clues by definition.
Step-by-step explanation:
The item that is not an example of a context clue is: a. Simile. Context clues are hints found within a sentence, paragraph, or passage that a reader can use to understand the meanings of new or unfamiliar words. A simile is a figure of speech that compares two different things, often introduced with the words 'like' or 'as'. It is not used to define a word but rather to compare and create a vivid image. An antonym serves as a context clue when an opposite word is used to help define the unfamiliar word. Inference is a process of reasoning and drawing conclusions based on the information provided, not a direct clue to a word's meaning, but it can help in understanding. A definition, of course, is when the word's meaning is explained directly within the passage.
On an unrelated note, answer to the example question would be d. suggestion, as it is the closest meaning to hypothesis. Moreover, part of a scientific poll design does not typically include a. a leading question, since it biases the results, whereas b. a random sample is crucial for the integrity of poll results.