Observe the following reactions:
$I$. $N_{2(g)} + 3H_{2(g)} \xrightarrow[773 \ K, \ 200 \ atm]{X} 2NH_{3(g)}$
$II$. $CO_{(g)} + H_{2}O_{(g)} \xrightarrow[673 \ K]{Y} CO_{2(g)} + H_{2(g)}$
$III$. $CH_{4(g)} + H_{2}O_{(g)} \xrightarrow[1270 \ K]{Z} CO_{(g)} + 3H_{2(g)}$
Catalysts $X$,$Y$,and $Z$ respectively are:

• A
  Iron,sodium arsenite,cobalt
• B
  Iron,zinc,cobalt
• C
  Cobalt,zinc,nickel
• D
  Iron,iron chromate,nickel