Identify $A$ and $B$ in the following reaction:
$CH_3-CH_3 \stackrel{B}{\longleftarrow} CH_3COOH \stackrel{A}{\longrightarrow} CH_3CH_2OH$
$A \quad B$

• A
  $HI + \text{red } P \quad LiAlH_4$
• B
  $Ni / \Delta \quad LiAlH_4$
• C
  $LiAlH_4 \quad HI + \text{red } P$
• D
  $Pd-BaSO_4 \quad Zn + HCl$