The best answer here is Answer C - Tab stops are useful when you want to "align text into columns".
All tab stops do is shift text a fixed amount to the left or right on the line. They are useful for improving the layout of text when you want to align multiple rows.
Answer A is incorrect because rows are vertical and not horizontal. B is also irrelevant because spaces between paragraphs are vertical. Answer D could also be correct because you can use tab stops to indent text aswell, but the more general answer is A. If you can have more than one answer, you could have A and D.
Answer; Electric Paper Display
Explanation:
<em>"PDs are extremely thin and only require power when a new image is requested. Instead of a traditional display that uses backlighting to illuminate pixels, an EPD is based on the scientific phenomena known as "electrophoresis," the movement of electrically charged molecules in an electric field."</em>
Above is the definition, as you can see it resembles your question greatly so this is most likely the answer you're looking for.
Good luck :D
It converts the mic input into a string of raw data, then compares it to hundreds, even thousands of voice samples. The output is a polished string of data in words.