If class A inherits class B then class A is called the ___________.

Suppose you have two classes called Flight and Passenger. What is the best relationship you can create between the two classes?

Which line indicate AUTOUNBOXING in the code snippet below?

ArrayList<Double> grades = new ArrayList<Double>();
grades.add(3.2);  // Line 1
grades.add(2.7);  // Line 2
double sum = 0.0; // Line 3
for (int i=0; i < grades.size(); i++) {
    sum += grades.get(i);  // Line  4
    System.out.println("Sum = " + sum);
}