Answer: B
Violet FeClX3 colour shows X is a cresol. Tribromination (three free positions ortho/para to −OH: 2, 4, 6) occurs only for 3-methylphenol, whereas 2- and 4-methylphenol have only two such positions. Y with no acidic or O−H group is the ether methoxybenzene, and Z, a primary alcohol oxidised to benzaldehyde, is phenylmethanol.