If you want to learn more about a command, point to its button and wait for the to appear.

The answer to this question is "Screen Tip".

Explanation:

In the operating system, there are many software. In this software, there is an option of the screen tip. screen tip is a small window that displays detailed text.

For example :  

If we start a paint software and we point the mouse on the pencil tool it display the detail of that tool like "Draw free-from line with a selected line width".

answer; i believe its compare (b3: b4) ;

answer; ///i believe that neither technician a or technician b are correct answer(both are false);