The correct option is D 1 : 1
Let the required ratio be k:1, then the coordinates of the point which divides the join of the points (-2, 4, 7) and (3, -5, 8) in this ratio are given by (3k−2k+1,−5k+4k+1,8k+7k+1)
As this point lies on the plane 2x - 1 = 0.
(3k−2k+1=12⇒k=1) and thus the required ratio as 1:1.