$Assertion (S)$: Ernest Chain and Howard Florey were awarded the Nobel Prize in $1948$.
$Reason (R)$: Lactic acid is produced by the fungus $Aspergillus$ $niger$.

• A
  $S$ and $R$ are both true, and $R$ is the correct explanation of $S$.
• B
  $S$ and $R$ are both true, but $R$ is not the correct explanation of $S$.
• C
  $S$ is true and $R$ is false.
• D
  $S$ and $R$ are both false.