Final answer:
The correct word to fill the blank is 'They're', abbreviated form of 'they are', which fits perfectly in the sentence structure and meaning.
Step-by-step explanation:
The completion of the sentence requires the correct usage of a pronoun. In the given sentence, '__ confident that with enough study they can easily pass the final exam', the right word will represent 'they'. So the answer will be D. They're, which is a contraction of 'they are'. Using this choice reflects the confident state of 'they'. It is, therefore, important to choose the right pronoun for proper sentence construction.
To understand this more, let's look at the differences between the options given. A. 'They have' is incorrect as it doesn't make sense in this context. B. 'There' is used to indicate place and isn't suitable here. C. 'Their' is a possessive pronoun meaning it suggests ownership. In this case, it's not correct because the part after the blank does not refer to something they possess. D. 'They're', however, fits perfectly as it represents 'they are' and completes the sentence to mean 'They are confident that with enough study they can easily pass the final exam'.
Learn more about Pronoun Usage