Write the recursive Running time equation

What is the number of subproblems in the recursive equation $?$

What is the size of each subproblem in the recursive equation $?$

What is the base case of this program? What is the running time of base case $?$

Program $3$:

$//$ comment: $n$ is a positive integer in this program

Function Fibonacci $($int n$)$:

if $(n==0)$

Print $("0")$

Return $0$

if $(n==1)$

Print $("1")$

Return $1$

Else $($n$>1)$:

Print $("$ Hello World $")$

Return Fibonacci$($n$-1)+$ Fibonacci$($n$-2)$