"Casual" refers to something relaxed, informal, or not strict. The antonym "Formal" denotes something that is official, structured, or follows established conventions. Therefore, option (C) Formal is the opposite or antonym of "Casual."

"Conceit" refers to an excessive sense of self-importance or pride, often accompanied by an overestimation of one's abilities. The antonym, "Modesty," represents a quality of being humble, unassuming, and free from excessive pride or self-assertion. Therefore, option (C) Modesty is the opposite or antonym of "Conceit."

The most appropriate antonym for the underlined word "blessed" in the given sentence is "cursed." "Blessed" implies being favored, protected, or endowed with divine grace, while "cursed" suggests being subjected to divine displeasure or misfortune. The other options— "appointed" (designated for a specific role), "produced" (created), and "applied" (put into action)— do not convey the opposite meaning of "blessed" in this context.

The most appropriate antonym for "sinks" in the given sentence is "floats." In the context of the sentence, "sinks" likely refers to the opposite action of floating. The other options— "create" (make), "parade" (a public procession), and "strolling" (walking leisurely)— are not antonyms of "sinks" in this context.

The most appropriate antonym for "rebellion" is "loyalty." Rebellion involves resisting or opposing authority, while loyalty implies faithfulness and allegiance to a person, group, or cause. The other options— "uprising" (an act of resistance or rebellion), "sedition" (incitement to rebellion), and "allotment" (the action of allotting or assigning something)— are either synonyms or closely related to the concept of rebellion.

The most appropriate antonym for "hospitality" is "coldness." Hospitality refers to the warm and friendly reception and treatment of guests, so "coldness," which implies a lack of warmth or friendliness, serves as the opposite. The other options— "complaint" (a statement expressing dissatisfaction or annoyance), "cordiality" (warmth and friendliness), and "wrathful" (full of or characterized by intense anger)— do not convey the opposite meaning of "hospitality" in this context.

The most appropriate antonym for "trivial" in the given sentence is "serious." "Trivial" refers to something of little importance or significance, so the opposite would be something of great importance or seriousness. The other options— "underrated" (underestimated), "kind" (having a gentle nature), and "problematic" (posing a problem or difficulty)— do not convey the opposite meaning of "trivial" in this context.