Pressing [Spacebar] changes the cursor to which tool?

A Stack interface is defined and has an isEmpty() abstract method. What should this method return?

a) an int representing the number of items in the stack b) a double representing the average of the values of the items in the stack c) a String representing the contents of the items in the stack. d) a boolean value representing whether the stack is empty or not. e) the item that is at the top of the stack

Case-Based Critical Thinking Questions ? Case 16-1 Jack is a computer programmer who spends most of the day at his desk. Recently, he visited the doctor to get advice about his persistent eyestrain and aching back. To combat his eyestrain, Jack's doctor correctly advises him to ____.

A. use a footrest B. use a lower screen resolution C. turn down the volume when using headphones D. use a light touch on the keyboard