The answer is:
d. making educated guesses as to the meaning of difficult words.?
Context clues are hints that an author provides to help illustrate a difficult or unusual word. They may appear within the same sentence or in a nearby sentence in relation to the word they refer to. Besides, an educated guess indicates an assumption based on knowledge and experience, which is therefore likely to be correct. As a result, context clues aids readers to make inferences about unknown vocabulary.