In This Acid-Base Equilibrium, the PK_a Values of the Two $$\frac { 1 } { 5 }$$

In this acid-base equilibrium, the pK_a values of the two acids are 4.8 and 9.8, but you must decide which is which from your knowledge of approximate pK_a values.
What is the equilibrium constant for this reaction?

A) −5
B) +5
C) 10^-5
D) 10⁺⁵
E)
$$\frac { 1 } { 5 }$$