Many banks have a drive-through automated teller machine, built into the wall flanking the driver' s side of a narrow aisle. Even though blind people obviously do not drive, these machines nonetheless invariably feature Braille -- the system of raised dots used by the blind for reading and writing -- in addition to the standard letters and numerals on their control panels. Which of the following, if true, does the most to explain the situation described? ['Moderately visually impaired people who are still allowed to drive typically do not use Braille to read or write.', 'Blind people can often read Braille just as quickly and accurately as sighted people can read regular writing.', 'The embossing technique used to form the raised dots does not typically add much to the overall cost of the automated teller machine.', 'In order to maximize profits per unit, manufacturers produce only a single model of automated teller machine.']