=[Amount]-[Down_Pay] is an example of conditional formatting

What are well-known ports?

What will be an ideal response?

What exception type does the following program throw?

``` public class Test { public static void main(String[] args) { Object o = null; System.out.println(o.toString()); } } ``` a. ArithmeticException b. ArrayIndexOutOfBoundsException c. StringIndexOutOfBoundsException d. ClassCastException e. NullPointerException