(1) The house was dark and quiet. (2) It was the perfect time of day to snuggle up with a good book. (3) Just as I pulled a quilt
over my lap, I heard a loud thud from upstairs. (4) Thinking that I had left the window open, I decided to investigate. (5) My
mind wandered as I mounted the stairs. (6) What would I do if there were someone in the house? (7) My heart started to beat
faster. (8) Finally, I reached the top of the stairs. (9) I slowly opened the bedroom door.
Which of these BEST replaces sentence 7 with descriptive detail?