How does listening to a repeated phrase such as “Let my people go” in “Go Down, Moses” help convey the spiritual’s mood and message?

a. The repetition dulls listeners’ ears to key messages of the spiritual.
b. The phrase reminds listeners that the slaves’ plight is similar to that of the Israelites. c. The phrase is a demand and helps convey a mood of determination.
d. The repetition of such phrases could be decoded to reveal hidden messages.