What are $\underline{A}, \underline{B}, \underline{C}$ in the following reactions?
$(I)$ $(CH_3 CO_2)_2 Ca \xrightarrow{\Delta} \underline{A}$
$(II)$ $CH_3 CO_2 H \xrightarrow[Red\ P]{HI} \underline{B}$
$(III)$ $2 CH_3 CO_2 H \xrightarrow{P_4 O_{10}} \underline{C}$
$\underline{A} \quad \underline{B} \quad \underline{C}$

• A
  $C_2 H_6 \quad CH_3 COCH_3 \quad (CH_3 CO)_2 O$
• B
  $(CH_3 CO)_2 O \quad C_2 H_6 \quad CH_3 COCH_3$
• C
  $CH_3 COCH_3 \quad C_2 H_6 \quad (CH_3 CO)_2 O$
• D
  $CH_3 COCH_3 \quad (CH_3 CO)_2 O \quad C_2 H_6$