Answer: C) encouraging.
Step-by-step explanation: the tone of a poem or a text is the author's attitude towards the audience, the subject or even the characters of the text. There are many different kinds of tones, positive, negative, happy, sad, angry, etc. In the given lines from the poem "love after love" we can see that the speaker's tone is encouraging, he is encouraging the audience to love and give back to the person that has loved you.