The van't Hoff factor (i) is highest for KHSO4 as it dissociate into its ions. van’t Hoff factor is the ratio of total number of ions produced after complete dissociation to before dissociation. Hydrazine, glucose and glycine will not dissociate to produce ions. Whereas, KHSO4 dissociates into ions. KHSO4→K++HSO4− Hence, i will highest for KHSO4. ∴ Colligative property i.e. freezing point depression will be highest for KHSO4 as ΔTf∝i [∵ m is constant i.e. 0.1] Hence, correct option is (d).