` vec p , vec q ,a n d vec r` are three mutually perpendicular vectors of the same magnitude. If vector ` vec x` satisfies the equation ` vec pxx(( vec x- vec q)xx vec p)+ vec qxx(( vec x- vec r)xx vec q)+ vec rxx(( vec x- vec p)xx vec r)=0,t h e n vec x` is given by `1/2( vec p+ vec q-2 vec r)` b. `1/2( vec p+ vec q+ vec r)""` c. `1/3( vec p+ vec q+ vec r)` d. `1/3(2 vec p+ vec q- vec r)`

Options

A. `1/2 (vec p + vec q - 2 vec r)`
B. `1/2 (vec p + vec q + vec r)`
C. `1/3 (vec p + vec q + vec r)`
D. `1/3 (2vec p + vec q - vec r)`