Here are the answers to your questions:
Question 1
A) What is a plot diagram?
Answer: the five elements of plot that stories usually include
Question 2
A) What is an inciting incident?
Answer: an event that introduces conflict during rising action
Question 3
A) What is a flashback?
Answer: a scene that interrupts the story’s chronological flow to tell events from the past
Question 4
A) How could the writer create dramatic irony to increase tension?
Answer: by revealing the killer’s identity to readers right before the detective unknowingly enters a scene with the killer
Question 5
A) How might the parallel plots intertwine to add a sense of mystery?
Answer: Events could become illogical at times in both realities to make the reader question what is really happening before the final reveal.
Feel free to ask if you need further assistance!