Select a Counterexample for the Given Invalid Argument

select a counterexample for the given invalid argument.
-1. (∀x) (Mx ⊃ Nx)
2) (∃x) (Mx • Ox)
3) Oa / Oa • Na

A) Counterexample in a domain of 2 members, in which: Ma: False Na: False Oa: True
Mb: True Nb: False Ob: True
B) Counterexample in a domain of 2 members, in which: Ma: False Na: False Oa: False
Mb: True Nb: False Ob: True
C) Counterexample in a domain of 2 members, in which: Ma: False Na: False Oa: True
Mb: True Nb: True Ob: True
D) Counterexample in a domain of 2 members, in which: Ma: True Na: True Oa: True
Mb: True Nb: True Ob: True
E) Counterexample in a domain of 2 members, in which: Ma: False Na: False Oa: True
Mb: False Nb: True Ob: True