The correct option is C P2 and P3 are perpendicular.
Given planes:
P1:2x−4y+6z=5P2:−x+2y−3z=8P3:3x+6y+3z=24.
D.r′s of normal to plane P1=(2,−4,6)
D.r′s of normal to plane P2=(−1,2,−3) and
D.r′s of normal to plane P3=(3,6,3)
As, D.r′s of planes P1 and P2 are proportional but not proportional to P3
So, planes P1 and P2 are parallel.
And, for plane P2,P3:a2a3+b2b3+c2c3=0
So, plane P2 and P3 are perpendicular.