If F(n) = O(g(n)) and G(n) = O(f(n)), What Else

Multiple Choice

If f(n) = O(g(n) ) and g(n) = O(f(n) ) , what else must be true?
I f(n) = Ω(g(n) )
II g(n) = Ω(f(n) )
III f(n) = θ(g(n) )

A) I
B) II
C) I and II
D) I, II, and III