Which solutions have a pH less than 7?

I.     ${\text{N}}{{\text{a}}_2}{\text{C}}{{\text{O}}_3}({\text{aq)}}$

II.     ${\text{[Fe(}}{{\text{H}}_2}{\text{O}}{{\text{)}}_6}{\text{]C}}{{\text{l}}_3}{\text{(aq)}}$

III.     ${{\text{(N}}{{\text{H}}_4}{\text{)}}_2}{\text{S}}{{\text{O}}_4}{\text{(aq)}}$

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

C