"Absurd" means wildly unreasonable or illogical, so the opposite or antonym would be "Reasonable," which denotes something logical and sensible. Therefore, option (D) Reasonable is the most suitable antonym in this context.

"Insatiable" refers to an inability to be satisfied or appeased. The opposite or antonym would be "Fulfilled," indicating a state of being satisfied or content. Therefore, option (B) Fulfilled is the most suitable antonym in this context.

"Flabby" describes something that is soft, loose, or lacking firmness. Therefore, "Firm" is the opposite, indicating solidity or a lack of flabbiness.

"Primitive" refers to something that is simple, basic, or undeveloped. On the other hand, "Sophisticated" implies complexity, refinement, and advanced development. Therefore, option (C) Sophisticated is the opposite or antonym of "Primitive."