Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Finest gold is red in colour,as the size of the particles increases,it appears purple then blue and finally gold.
Assertion $R$: The colour of the colloidal solution depends on the wavelength of light scattered by the dispersed particles.
In the light of the above statements,choose the most appropriate answer from the options given below:

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