The document presents a problem involving 3D geometry, where the intersection of a line joining points q(2,3,5) and r(1,-1,4) with the plane 5x-4y-z=1 is calculated, along with the foot of the perpendicular from point t(2,1,4) to line qr. It includes a detailed breakdown of the mathematical equations and coordinates involved, ultimately leading to the length of the line segment ps being derived as 1. The correct option for the problem is indicated as (a).