An Aqueous Solution of Boric Acid Can Be Represented by the Equilibrium

Multiple Choice

An aqueous solution of boric acid can be represented by the equilibrium system:
B(OH) ₃(aq) + 2 H₂O(l) ⇌ H₃O⁺(aq) + B(OH) ₄^-(aq) (K_a = 5.6 × 10^-10)
What is the pH of an eyewash solution which is 0.0018 M in boric acid?

A) 3.75
B) 4.75
C) 6.00
D) 7.49
E) 9.25