{"knowledge_schema": {"broad_category": "Chemistry \u2192 Organic Chemistry \u2192 Reaction Mechanisms", "refinement": "This problem involves identifying starting materials that undergo specific chemical transformations when treated with hydrochloric acid, sodium nitrite, and water.", "specific_scope": "The focus is on the synthesis of diketones from specific ketones through a reaction involving diazotization and subsequent hydrolysis.", "goal": "Select the correct starting materials C and D that will yield the specified diketones upon treatment."}, "summary": "This problem requires understanding organic reactions, specifically the transformation of ketones into diketones through treatment with hydrochloric acid and sodium nitrite. The task is to identify the correct starting materials from a list of candidates that will produce the desired diketones. The correct answer is C = 3-ethylcyclopent-2-one and D = 4-ethyl-2-pentanone, as these compounds can undergo the specified reactions to yield the corresponding diketones."}