1Z0-809 Question #64: Real Exam Question with Answer & Explanation

Given the following code and code fragment:

class Sum extends RecursiveAction { //line n1
 static final int THRESHOLD_SIZE = 3;
 int stIndex, lsIndex;
 int [] data;
 public Sum(int []data, int start, int end) {
 this.data = data;
 this.stIndex = start;
 this.lsIndex = end;
 }

 protected void compute () {
 int sum = 0;
 if (lsIndex ? stIndex<= THRESHOLD_SIZE) {
 for (int i = stIndex; i < lsIndex; i++) {
 sum = data [i];
 }
 System.out.println(sum);
 } else {
 new Sum (data, stIndex + THRESHOLD_SIZE, lsIndex).fork();
 new Sum (data, stIndex,
 Math.min (stIndex, stIndex + THRESHOLD_SIZE)
 ).compute ();
 }
 }
}

And the code fragment:

ForkJoinPool fjpool = new ForkJoinPool ();
int data [] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
fjpool.invoke (new Sum (data, 0, data.length));

And given that the sum of all integers from 1 to 10 is 55. Which statement is true?