Part a: what is the meaning of “iniquity” in paragraph 5?

Iniquity is a noun that means something immoral, unjust or wicked

Explanation:

This is a more literary (used in novel and literature) way to described something that represent a wrongdoing, or even a sin.  It is rarely used in everyday speech.

It could be replaced by words like vice, immorality or corruption.

For example:

It is iniquity that led to his downfall.

Or In other words:

b. his ability to use formal language to stress strong feelings

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."