Choice D is the best answer. The narrator states that Crimsworth dislikes him because the narrator may"one day make a successful tradesman" (line 43,"too ...tradesman"). Crimsworth recognizes that the narrator is not "inferior to him" but rather more intelligent, someone who keeps "the padlock of silence on mental wealth which [Crimsworth] was no sharer" (lines 44-48,"Had...sharer"). Crimsworth feels inferior to the narrator and is jealous of the narrator's intellectual and professional abilities.
Choices A and C are incorrect because the narrator is not described as exhibiting "high spirits" or "rash actions," but "Caution, Tact, [and] Observation" (line 51,"faculties...prowling"). Choice B is incorrect because the narrator’s "humble background" is not discussed.