Consider two functions $f(n)$ and $g(n).$ Which of the following statements is

true?

If $f(n)in(g(n)),$ then we must have $f(n)in(g(n))$ but

$f(n)!in(g(n))$

If $f(n)inO(g(n)),$ then we must have $f(n)ino(g(n))$ and

$f(n)in(g(n))$

If $f(n)in(g(n)),$ then we must have $f(n)in(g(n))$ and

$f(n)ino(g(n))$

If $f(n)ino(g(n)),$ then we must have $f(n)inO(g(n))$ but

$f(n)!in(g(n))$