What Is the Approximate Value of the Equilibrium Constant,K_n,for the Neutralization

What is the approximate value of the equilibrium constant,K_n,for the neutralization of acetic acid with sodium hydroxide,shown in the equation below? The K_a for acetic acid is 1.8 × 10^-5.
CH₃CO₂H(aq) + NaOH(aq) ⇌ H₂O(l) + NaCH₃CO₂(aq)

A) 1) 8 × 10^-19
B) 5) 6 × 10^-10
C) 1) 8 × 10^-8
D) 1) 8 × 10⁹