Which is not a conjugate acid-base pair?

A.     ${\text{HN}}{{\text{O}}_{\text{3}}}$ and ${\text{NO}}_3^ -$

B.     ${\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}}$ and ${\text{C}}{{\text{H}}_{\text{3}}}{\text{CO}}{{\text{O}}^ - }$

C.     ${{\text{H}}_{\text{3}}}{{\text{O}}^ + }$ and ${\text{O}}{{\text{H}}^ - }$

D.     ${\text{HSO}}_4^ -$ and ${\text{SO}}_{{\text{42}}}^{2 - }$

C