Consider the recursive method folderUsage() below, where is the base case of the method? Explain how the base case works in this method. You can refer to the line numbers in your explanation. 52 public double folderUsage (File folder) { 53 54 double total = folder.length(); 55 56 57 58 59 60 61 62 63 64 65 } if (folder.isDirectory()) { for (String childname : folder.list()) { File child = new File(folder, childname); total + folderUsage (child); } } 11 System.out.println(total + return total; "I + folder);