What is the concentration of the hydroxide ion given the concentration of the hydronium ion is 2.5 x 10⁻⁵ M?
A) 2 x 10⁻¹⁰
B) 4 x 10⁻¹⁰
C) 2 x 10⁻⁹
D) 4 x 10⁹
E) none of the above