To turn the visibility for layers on and off, you can press ____ on the visibility icon for the layer you wish to view.

A __________ is a section of code that the programmer writes once, and then can use many times.

A. macro expansion B. directive C. macro definition D. subroutine

?Identify the character entity reference that can be used to force Hypertext Markup Language (HTML) to display an extra white space.

A. ?  B. ? C. ? D. ?