Friedel-Crafts acylation occurs para to OCH3; the chain then cyclises ortho to the chain (meta to OCH3) and the C=O is removed by Clemmensen reduction.
Anisole + succinic anhydride/AlCl3: the acyl group enters para to the activating OCH3, giving 4-(4-methoxybenzoyl)butanoic acid (A). Clemmensen reduction converts C=O to CH2; the chain is then cyclised by an intramolecular Friedel-Crafts step onto the ring position ortho to the chain (meta to OCH3), and the ketone formed is again reduced, giving a tetralin. The OCH3 is therefore on the carbon one removed from the ring-fusion carbon (not adjacent to it), and the product has no OH groups. This matches the methoxy-tetralin drawn in option (4); option (3) has OCH3 next to the fusion carbon and options (1), (2) contain OH groups. Answer: (4) the methoxy-tetralin drawn in option (4)
