Answer:
D. ignorance.
Step-by-step explanation:
A derogatory tone means a kind of tone that has negative or pejorative connotations, whereas a comforting tone would be one characterized by empathy, acceptance and joyous affirmation, even in the face of hardships.
To change the tone of the passage above into a comforting one, you should change the word ignorance for something of an empathetic nature. A good example could be “wisdom”, so that the sentence would read: your pain is a cruel testimony of your wisdom.