Which of the following is an invalid call to thefunction above?
a. examplerecursion(-1)
b. examplerecursion( 0)
c. examplerecursion(1)
d. examplerecursion(999)
int func1(int m, int n) {
if (m==n || n==1)
return 1;
else
return func1(m-1,n-1) + n*func1(m-1,n);
}