In "the notorious jumping frop of the calveras country" which plot point is part of the frame story?

Which word best describes the author's tone in this excerpt from "that spot" by jack london? i don’t think much of stephen mackaye any more, though i used to swear by him. i know that in those days i loved him more than my own brother. if ever i meet stephen mackaye again, i shall not be responsible for my actions. it passes beyond me that a man with whom i shared food and blanket, and with whom i mushed over the chilcoot trail, should turn out the way he did. i always sized steve up as a square man, a kindly comrade, without an iota of anything vindictive or malicious in his nature. i shall never trust my judgment in men again. why, i nursed that man through typhoid fever; we starved together on the headwaters of the stewart; and he saved my life on the little salmon. and now, after the years we were together, all i can say of stephen mackaye is that he is the meanest man i ever knew. a. excited b. ironic c. indignant d. playful