Q15. Which of these is a variation of ADSL, but the modem can adjust the speed of the connection depending on the length and quality of the line:

Вариант ответа 1 - a) VDSL

Вариант ответа 2 - b) SDSL

Вариант ответа 3 - c) RADSL

Вариант ответа 4 - d) None of These