Consider the following multithreaded Java program. What should be done to fix this code?

A. Nothing needs to be fixed.

B. The Sum class should be replaced with a global variable, to simplify the code.

C. The run() method in the thread object "thrd" is never called in this code, it should be called.

D. Both modifications in B and C should be done.

class Sum { private int sum; public int getSum() { return sum; } public void set Sum(int sum) { this.sum - sum; } } class Summation implements Runnable { private int upper; private Sum sumValue; public Summation (int upper, Sum sumValue) { this.upper - upper; this.sumValue = sumValue; } public void run() { int sum = 0; for (int i = 0; i 0) { if (Integer.parseInt (args[0]) = 0."); else { Sum sumobject = new Sum(); int upper - Integer.parseInt (args[0]); Thread thrd = new Thread (new Summation (upper, sumobject)); thrd.start(); try { thrd.join(); System.out.println ("The sum of "+upper+" is "+sumobject.getSum()); } catch (InterruptedException ie) { } } else System.err.println("Usage: Summation integer value>"); }