Answer :
b. enhance the natural setting
d. assert the brevity of happiness
b. "And Joy, whose hand... while the bee-mouth sips," enhances the natural setting by describing the imagery of Joy and Melancholy within a natural context, evoking a sense of the fleeting beauty and transience of happiness.
d. The phrase "while the bee-mouth sips" suggests the brevity of happiness by comparing it to the quick and ephemeral act of a bee sipping nectar from a flower. This assertion of the brevity of happiness aligns with the overall theme of the poem, which explores the transient nature of human emotions and experiences.
