`P` is a point on the line through the point `A` whose position vector is ` vec a` and the line is parallel to the vector ` vec b` . If `P A=6,` the position vector of `P` is: (a)` vec a+6 vec b` (b) ` vec a+6/(| vec b|) vec b` (c)` vec a-6 vec b/(| vec b|)` (d) ` vec b+6/(| vec a|) vec a`