What Does the Following Method Compute? Assume the Method Is

Multiple Choice

What does the following method compute? Assume the method is called initially with i = 0
Public int question9(String a, char b, int i)
{
If (i = = a.length( ) ) return 0;
Else if (b = = a.charAt(i) ) return question9(a, b, i+1) + 1;
Else return question9(a, b, i+1) ;
}

A) the length of String a
B) the length of String a concatenated with char b
C) the number of times char b appears in String a
D) returns 1 if char b appears in String a at least once, and 0 otherwise
E) the char which appears at location i in String a