_____ uses a command-line interface to communicate with users by default.

When a subclass constructor calls its superclass constructor, what happens if the superclass’s constructor does not assign a value to an instance variable?

a. A syntax error occurs. b. A compile-time error occurs. c. A run-time error occurs. d. The program compiles and runs because the instance variables are initialized to their default values.

The practice of searching the Internet for unprotected computers is called a(n) ____________________.

Fill in the blank(s) with the appropriate word(s).