Step 1: Analyzing the E2 elimination step. The bromoalkane reacts with alcoholic KOH under heat, undergoing β-elimination where a base abstracts an anti β-hydrogen, expelling bromide and forming the most substituted, stable internal alkene per Zaitsev's rule. Step 2: Alkene intermediate formation. Deprotonation opposite to the leaving group yields a more highly alkylated olefin as the major unsaturated intermediate. Step 3: Ozonolysis procedure. Treatment with O₃ followed by Zn/H₂O reductively cleaves the carbon-carbon double bond, transforming each olefinic carbon into a carbonyl compound—ketone for disubstituted carbons, aldehyde for terminal ones. Step 4: Deduction of cleavage fragments. The unsymmetrical alkene furnishes a ketone from the more substituted carbon and an aldehyde from the less substituted end, matching the skeleton depicted in option (4). Step 5: Final confirmation. Only option (4) correctly reflects both the regiochemistry of elimination and the oxidative cleavage pattern.
