The values of ${K_{\text{w}}}$, the ionic product constant of water, are:

Which statements are correct?

I.     The ${\text{[O}}{{\text{H}}^ - }{\text{]}}$ in water is less than the ${\text{[}}{{\text{H}}^ + }{\text{]}}$ at 18 °C.

II.     The ionization of water is an endothermic process.

III.     The pH of water is lower at 25 °C than at 18 °C.

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

C