Which of the following is Clemmensen reduction?

• A
  $>C=O + 4[H] \xrightarrow{Zn-Hg / \text{conc. } HCl / \Delta} >CH_2 + H_2O$
• B
  $-COCl \xrightarrow{H_2 / Pd-BaSO_4} -CHO + HCl$
• C
  $-CH=O$ $\xrightarrow{H_2N-NH_2 / -H_2O} R-CH=N-NH_2$ $\xrightarrow{KOH / \text{ethylene glycol} / \Delta} -CH_3 + N_2$
• D
  $-C \equiv N + 2[H]$ $\xrightarrow{SnCl_2 / \text{dil. } HCl} -CH=NH \cdot HCl$ $\xrightarrow{H_3O^+} -CHO + NH_4Cl$