Consider the following code. After the main method executes, the final values in the counts array are not guaranteed to be 2000 for each element. Which statement best explains why the expected values might not be achieved?

public class AtomicMistake {
    private int[] counts = new int[2];
    
    public void incrementBoth() {
        counts[0]++;
        counts[1]++;
    }
    
    public static void main(String[] args) {
        AtomicMistake am = new AtomicMistake();
        Runnable task = () -> {
            for (int i = 0; i < 1000; i++) {
                am.incrementBoth();
            }
        };
        Thread t1 = new Thread(task);
        Thread t2 = new Thread(task);
        t1.start();
        t2.start();
    }
}