Vector Algebra: JEE Main 2016 Mathematics question

In a triangle ABC, right angled at the vertex A, if the position vectors of A, B and C are respectively 3$\widehat i$ + $\widehat j$ $-$ $\widehat k$,   $-$$\widehat i$ + 3$\widehat j$ + p$\widehat k$ and 5$\widehat i$ + q$\widehat j$ $-$ 4$\widehat k$, then the point (p, q) lies on a line :