The aromatic amine shown is diazotised at 0-5 ${}^{\circ }$C and the solution is then warmed with water. Which structure is the product?

The compound shown is 3-methylaniline. Diazotisation gives the diazonium salt, which on warming in water is hydrolysed (nucleophilic substitution by water with loss of $\mathrm{N}{}_2$) at the same ring carbon. The hydroxyl takes the position of the diazonium group, giving 3-methylphenol (m-cresol).