"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.

"Difference" implies a degree of dissimilarity or distinction, and "Similarity" represents the opposite, indicating things that are alike or have common features. Therefore, option (A) Similarity is the most suitable antonym in this context.

"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."