{"knowledge_schema": {"broad_category": "Chemistry \u2192 Organic Chemistry \u2192 Stereochemistry", "refinement": "This problem focuses on the concept of optical activity, which is determined by the presence of chiral centers in organic compounds.", "specific_scope": "The task involves analyzing a list of compounds to identify which ones possess chirality and thus exhibit optical activity.", "goal": "Determine the number of compounds that are optically active based on their structural characteristics."}, "summary": "This problem requires understanding the concept of optical activity in organic chemistry, specifically identifying chiral centers in various compounds. A compound is optically active if it has at least one chiral center, meaning it cannot be superimposed on its mirror image. By analyzing the provided compounds, we can determine that three of them exhibit optical activity due to their chiral centers, leading to the conclusion that the answer is 3."}