If you were writing this biography, you would most likely reasearch:

answer: "the beating heart symbolizes the narrator's conscience, or his sense of guilt and wrongdoing" so its b

explanation:

"to look at him, or hear him describe it, he had no guilt. however, poe decided to symbolize this man's subconscious guilt through the heartbeat."

the author develops a cold, and scared tone. making the reader shudder with fear, and suddenly become cold. i'm guessing that he's writing a scary novel, or maybe about a chilly december night.