Answer:
I believe its c.
Step-by-step explanation:
They mention how holding on to the metaphorical acid which represented the person's anger burned. Although, keeping the anger bottled up caused the person comfort, it caused them pain just as well. Now since the acid is metaphorical, it can't physically hurt the person so it cant be D(The other choice I was torn between). They also mention how the acid ate away the persons soul in a way (Still not mentioning anything about physical pain.)