The degree of dissociation of water at 25∘C is 1.9×10⁻⁷ and density is 1.0 g cm⁻³ The ionic constant for water is :
A.1.0×10⁻¹⁰
B.1.0×10⁻¹⁴
C.1.0×10⁻¹⁶
D.1.0×10⁻⁸