One way to develop a main idea to feature in your advertisement is to a. survey the audience b. format your layout c. develop a slogan d. conduct product research

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."

he has become more humble and patient in battle.