Please explain answer in detail. Thanks.

Problem 3 (20 points): Look at the following piece of java code that implements a simple recursive function: class Factorial \{ static int factorial ( int n ) \{ if ( n=0 ) return n factorial (n1);// recursive call else return 1 ; The function is then called by the main method listed below: public static void main(String [] args) \{ int number =4, result; result = factorial (number); System.out.println (number + " factorial = " + result); \} 3 a) What is the output of the program? b) How did the program arrive at the answer. Draw up the recursive tree to show your working