Which of the following is Clemmensen reduction?

Which of the following is Clemmensen reduction?
  1. $-\mathrm{CO}-+4[\mathrm{H}] \frac{\mathrm{Zn}-\mathrm{Hg} / \mathrm{conc.HCl}}{\Delta}-\mathrm{CH}_{2}-+\mathrm{H}_{2} \mathrm{O}$
  2. $-\mathrm{CO}-\mathrm{Cl} \frac{\mathrm{H}_{2}}{\mathrm{Pd}-\mathrm{BaSO}_{4}}-\mathrm{CHO}+\mathrm{HCl}$
  3. $-\mathrm{CH}=\mathrm{O} \frac{\mathrm{H}_{2} \mathrm{~N}-\mathrm{NH} 2}{-\mathrm{H}_{2} \mathrm{O}}{ }^{\mathrm{R}-\mathrm{CH}=\mathrm{N}-\mathrm{NH}_{2}}{\Delta}{ }^{\text {KOH/ethyleneglycol }}{ }_{\Delta}{ }^{-\mathrm{CH}_{3}}+\mathrm{N}_{2}$
  4. $-\mathrm{C} \equiv \mathrm{N}+2[\mathrm{H}] \underset{\text { dil HCl }}{\text { Sn Cl }_{2}}{\longrightarrow}-\mathrm{CH}=\mathrm{NH} \cdot \mathrm{HCl} \stackrel{\mathrm{H}_{3} \mathrm{O}^{+}}{\longrightarrow}-\mathrm{C}=\mathrm{O}+\mathrm{NH}_{4} \mathrm{Cl}$

Asked in: MHT CET 2020 (20 Oct Shift 1)

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