Future tenses test I think the exam… very difficult. is going to be is being

The correct choice for the sentence is "is going to be." So, the complete sentence would be: "I think the exam is going to be very difficult." This construction is used for predictions based on evidence or when you have a strong feeling about a future event. "Is being" would not fit in this context, as it's a present continuous tense typically used for ongoing actions rather than future events.