Identify the reagents $A$ and $B$ in the following reaction: $CH_3 CH_3 \leftrightarrow{(B)} CH_3 COOH \rightarrow{(A)} CH_3 CH_2 OH$

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