To effectively use the technique of setting out a problem in a narrative hook, the best choice is:
d. Make the problem interesting.
An interesting problem immediately grabs the reader's attention and compels them to want to know more. By presenting a problem that is intriguing, relatable, or unique, you can draw the reader into the narrative and encourage them to engage with the story. While the other options (large scale, frightening, complicated) can enhance the problem's impact, the key is that it must capture the reader's curiosity and make them eager to explore how it unfolds.