Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R.$
Assertion $A:$ $EM$ waves used for optical communication have longer wavelengths than that of microwaves employed in $RADAR$ technology.
Reason $R:$ Infrared $EM$ waves are more energetic than microwaves (used in $RADAR$).
In the light of the given statements,choose the correct answer from the options given below:

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