Suppose you have an ascii character that you know to be a letter. but you don't know whether it is upper-case or lower-case. what is the best way to transform this character (if needed) into a upper-case character? select one: take the two's complement of the original character. or the original character with the value xffdf. subtract #20 from the original character. or the original character with the value x20. and the original character with the value xffdf. subtract x20 from the original character. and the original character with the value x20.