Which of the following points lies on the directrix of the parabola x2−4x−8y+20=0x^2 - 4x - 8y + 20 = 0x2−4x−8y+20=0?
(0,1)(0, 1)(0,1)
(2,1)(2, 1)(2,1)
(5,1)(5, 1)(5,1)
(0,0)(0, 0)(0,0)