Coupling of benzene diazonium chloride with phenol yields colored compounds called azo dyes. The reaction requires

alkaline medium

The correct answer is Option (2) → alkaline medium

In azo coupling reactions, phenol couples with benzene diazonium chloride most effectively in an alkaline medium. The phenoxide ion formed in alkaline solution is more reactive toward electrophilic substitution, leading to the formation of azo dyes.