Following are statements of a few processes taking place in nature:
$I$. Free expansion of a gas
$II$. The combustion of a mixture of petrol and air ignited by a spark
$III$. The leaking of gas from the kitchen cylinder
$IV$. The transfer of heat from one heated part of a liquid to the other colder part
Which amongst these processes are irreversible in nature?

• A
  $I$ and $II$
• B
  $III$ and $IV$
• C
  $II$, $III$ and $IV$
• D
  $I$, $II$, $III$ and $IV$