This question is incomplete. Its full version is:
(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?
A) My heart began to race.
B) My heartbeat increased.
C) My heart seemed to beat out of my chest.
D) My heart started to beat much more rapidly.
Answer: the right option is C.
Descriptive details resort to the recreation of sensorial experiences in such a way that the reader can feel as if they were into the scene.
Hence, sentence 7 is best replaced by option C "my heart seemed to beat out of my chest" because it is the one that describes a physical reaction motivated by a given situation.