Explain the effect of concentration on equilibrium using the following experiment:
$Fe^{3+}_{(aq)} + SCN^{-}_{(aq)} \rightleftharpoons [Fe(SCN)]^{2+}_{(aq)}$
(Yellow) (Colourless) (Deep red)

• A
  Addition of $Fe^{3+}$ shifts the equilibrium to the right,increasing red color intensity.
• B
  Addition of $SCN^{-}$ shifts the equilibrium to the right,increasing red color intensity.
• C
  Both $(A)$ and $(B)$ are correct.
• D
  Addition of $HgCl_2$ shifts the equilibrium to the right.