Asymptotic bound of a recursive function Consider the following procedure computing a dummy function. Which one is a correct asymptotic bound for the running time of F(N) expressed in terms of N?

F(i):
    if i&lt;3then
        return 0 
    end if
    return F(i−1) + F(i−2)


$• A. O(N)
• B. O(N^2)
• C.O(2^N)
• D. O(N log(N))$



This may seem like a dumb question but I have no idea how to get asymptotic bounds for recursive methods. I got the following recurrence relation:
$T(n)=T(n-1)+T(n-2)$
but I'm not sure where to go from here. The answer is supposed to be C.
The recurrence relation $T(n) = T(n-1) + T(n-2)$, with initial conditions $T(2) = T(1) = 1$, has as solution the Fibonacci numbers, whose asymptotic growth is known to be $\Theta(\phi^n)$, where $\phi = \frac{1+\sqrt{5}}{2} &lt; 2$. The same bound holds for arbitrary positive initial conditions.