Identify $A$ and $B$ in the following reaction:
$CH_3-CH_3 \xleftarrow{B} CH_3COOH \xrightarrow{A} CH_3CH_2OH$

$A$

$B$

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