Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The alkali metals and their salts impart characteristic colour to reducing flame.
Reason $R$: Alkali metals can be detected using flame tests.
In the light of the above statements,choose the most appropriate answer from the options given below.

• A
  Both $A$ and $R$ are correct but $R$ is $NOT$ the correct explanation of $A$.
• B
  $A$ is correct but $R$ is not correct.
• C
  $A$ is not correct but $R$ is correct.
• D
  Both $A$ and $R$ are correct and $R$ is the correct explanation of $A$.