K_c Is 1

K_c is 1.67 × 10²⁰ mol³ L^-3 at 25 °C for the formation of iron(III) oxalate complex ion: Fe³⁺(aq) + 3C₂O₄^2-(aq) ⇌ [Fe(C₂O₄) ₃]^3-(aq)
If 0.0200 mol L^-1 Fe³⁺ is initially mixed with 1.00 mol L^-1 oxalate ion, what is the concentration of Fe³⁺ ion at equilibrium?

A) 1.44 × 10^-22 mol L^-1
B) 0.0100 mol L^-1
C) 8.35 × 10¹⁹ mol L^-1
D) 6.94 × 10²¹ mol L^-1