Choice A is the best answer. The narrator admits that his job is "irksome" (line 7,"felt ...the") and reflects on the reasons for his dislike. The narrator admits that his work is a "dry and tedious task" (line 9,"was ...been") and that he has a poor relationship with his superior: “the antipathy which had sprung up between myself and my employer striking deeper root and spreading denser shade daily, excluded me from every glimpse of the sunshine of life” (lines 28-31,"the ... life").
Choices B, C, and D are incorrect because the narrator does not become increasingly competitive with his employer, publicly defend his choice of occupation, or exhibit optimism about his job.