Saccharin Is a Monoprotic Acid $\times$ 10^-3 M Solution of This Acid Is 2

Multiple Choice

Saccharin is a monoprotic acid.If the pH of a 4.41 $\times$ 10^-3 M solution of this acid is 2.53,what is the K_a of saccharin?

A) 8.7 $\times$ 10^-6
B) 2.0 $\times$ 10^-3
C) 6.0 $\times$ 10^-3
D) 2.9 $\times$ 10^-3
E) none of these