Assertion $A$: In a herbarium,plant specimens are preserved and protected.
Reason $R$: Processes like poisoning and fumigation are performed on plant specimens.
Which option is correct for Assertion $A$ and Reason $R$?

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